Asia’s vast and varied geology has produced scenes that seem almost extraterrestrial. From striped, multicolored mountains to lava-heated valleys emitting clouds of steam, the continent’s terrain offers spectacles so bizarre they seem “not from this world.” This guide profiles seven such wonders – including China’s Rainbow Mountains, Nepal’s Gokyo Lakes, the Chocolate Hills of the Philippines, Indonesia’s tricolor Kelimutu Lakes, Vietnam’s Son Doong Cave, the Ban Gioc–Detian Falls on the Vietnam–China border, and Hokkaido’s steaming hot springs – weaving together their science, local lore, and practical visiting advice. Each entry explains why the site is so surreal, how it formed over geologic time, its cultural significance to local communities, and how travelers can experience it today. Expert sources and first-hand observations ensure a deep, accurate understanding of these remarkable sites.
The term “otherworldly” is often used informally to describe scenery that feels almost alien or surreal. Geologists might define such landscapes as those produced by extreme and unusual earth processes – tectonics, volcanism, erosion – that conspire to create rare forms, colors, or scales. Asia’s position on multiple tectonic plates and volcanic arcs makes it especially prone to such phenomena. For example, the collision of the Indian and Eurasian plates about 50 million years ago crumpled Tibet and raised the Himalayas to the tallest mountains on Earth. Much of East and Southeast Asia also lies along the Pacific “Ring of Fire,” a horseshoe of volcanic arcs and trenches that accounts for ~90% of the world’s earthquakes and 75% of its active volcanoes. These titanic geologic forces have not only built high mountains, but also caused uplifts, fractures, and exposures of rock layers that elsewhere lie buried.
Over millions of years, weathering and erosion by wind, water and ice sculpt these uplifted strata. What began as horizontal layers of sediment can be folded, tilted or eroded into cliffs, pillars, and wave-like ridges. Mineral-rich sediments deposited in ancient lakes or oceans can be stained vibrant hues when exposed at the surface. In glaciated valleys, pulverized rock (glacial “flour”) suspended in meltwater produces milky blue-green lake colors. Even the interplay of light and atmosphere alters our perception: a clear morning sun makes colors pop, while misty dawn can subdue the palette.
In short, sheer geologic rarity combined with dramatic sensory experience defines an “otherworldly” landscape. Such places often defy easy comparison: they may look like abstract paintings (stripes of red and green on mountainsides) or like scenes from science fiction (fog-enshrouded peaks, subterranean jungles, or steaming sulfur vents). Humankind’s evolutionary context – we evolved in temperate environments – means that encountering intensely alien terrain can trigger awe. Writers and travelers often note a sense of the “sublime” or profound respect in these settings, as if nature’s long timeline were suddenly visible.
Rising from the dry valleys of China’s Gansu Province, the Zhangye Danxia hills are among the world’s most vivid examples of sedimentary layering. From a distance, they appear to be vast candy-striped fields – reds, oranges, yellows, pinks, greens – laid out in broad, undulating bands across rounded hills. Seen up close at dawn or dusk, the layered strata glow with extra intensity, shifting hue with each passing cloud or sunbeam.
Geologically, the story begins over 100 million years ago in the Early Cretaceous. At that time this region was a low basin of lakes and rivers. Over some 8 million years (roughly 114–106 Mya), layers of sandstone and siltstone were deposited (much like pages of sediment in a slow-motion book). These sediments contain iron-rich minerals. After deposition, the entire stack of strata was lifted and tilted by tectonic forces – the same Eurasian-Indian plate collision that built the Himalayas also wrinkled and raised these layers.. Millions of years of uplift exposed the former lake and riverbeds to the elements. Rain, wind and freezing then eroded away the softer parts, rounding the hills. What remains are the harder colored layers, each representing sediments from a particular epoch..
The rainbow effect arises because each layer contains different minerals. The red and pink stripes are high in iron oxide (“rust”). Greenish layers contain chlorite or other clay minerals (often altered iron minerals). Yellow or brown may be from limonite (a type of iron oxide-hydroxide). Over countless seasons of rain and sun, these minerals oxidized (literally rusted) in place, fixing the colors into the rocks. In the science of color, suspended iron oxide makes rocks red; iron sulfides and chlorite produce yellow-green tones. The UNESCO Geopark nomination for Zhangye Danxia emphasizes that the color streaks were “painted” into the hills by successive deposition and weathering.
Photography Masterclass: The angle of sunlight profoundly affects visibility of the colors. Photographers often schedule Zhangye visits for shortly after rain in the late afternoon or at sunrise. Low-angle light washes the entire scene in warm tones and casts shadows that enhance the relief of ridges. On particularly clear days, vibrant reds and greens leap off the slopes. Some visitors find early morning (before 8 AM) ideal: the air is still, the valleys often misty, and colors gradually intensify. Conversely, midday sun (though bright) can bleach the colors on camera – but it also brings out subtle blues and purples in shaded crevices. When shooting, use a polarizing filter to deepen the sky and reduce haze. A wide-angle lens captures the vast panorama from the main viewing platforms; zoom or telephoto lenses can isolate patterns on specific hills.
From a practical standpoint, Zhangye is quite accessible. The site is now the Zhangye Danxia National Geopark, a protected area of over 500 km². Since 2019 it has been recognized as a UNESCO Global Geopark, underscoring its scientific value. A paved road leads to several viewing platforms at multiple elevations. Platforms are spaced along a ridge, and a shuttle bus (or a rented bike) can ferry visitors between them. Even a leisurely walk along the boardwalk can reveal dozens of color-striped knobs.
Local tourism sources note that summer to early autumn (June–September) is the best window to see the brightest colors, because spring rains have settled and the sky is clear. Winter (November–February) brings icy cold winds that can whip up sand, and the subdued angle of the sun yields less dramatic contrast. Crowds are lighter in off-peak months, but some shutterbugs prefer chasing the autumn hues. In any season, the vividness is often clearest after light rain, which washes dust off the hillsides. Expect an entrance fee (around RMB75 as of 2025) and park operating hours that may adjust for weather. There is now a visitor center with maps and geology exhibits, plus a small museum on-site.
Historically, this area was inhabited by nomadic tribes like the Qiang and Mongols; rock shelters in nearby gorges bear prehistoric cave art. The city of Zhangye itself was a Silk Road oasis town. Hui Muslim communities live in the region, blending Chinese and Central Asian cultures. Local guides sometimes explain the Danxia hills in folklore terms (red earth, yellow earth, etc.) alongside the science – a balance of earth and legend. Modern signage at the park emphasizes the longevity and fragility of the formation, warning visitors not to climb the hills (which could disrupt erosion patterns).
“Over the past 24 million years, the collision of the Indian and Eurasian plates has crafted Zhangye’s rainbow hills. Tilted upward, this ‘layer cake’ of colored sandstone has been sculpted by wind and rain into the graceful waves of Danxia landforms we see today”.
In Nepal’s Sagarmatha (Everest) National Park lies a cluster of high-altitude glacial lakes collectively known as Gokyo Lakes. A trek to these lakes offers a very different kind of “otherworldly” – not alien color bands, but an ethereal panorama of snow peaks reflected in mirror-like waters colored the blue-green of precious gems. Flanking the treacherous Ngozumpa Glacier and set at elevations of 4,700–5,000 m, these six (actually more, though six are main) lakes are often clear enough to mirror Everest, Cho Oyu and Lhotse on still days. Their color and holiness make them “sacred lakes” to Tibetan Buddhists and Hindus, who regard Gokyo as the abode of deities.
Milky turquoise waters of Thonak Tsho (the largest Gokyo Lake). The suspended glacial silt gives the lake its opaque blue-green hue, set against the snow-capped Himalaya.
The science of the color is straightforward: meltwater from the glacier grinds rock into very fine particles called “glacial flour.” When light penetrates the water, the fine silt scatters shorter (blue/green) wavelengths and absorbs others, making the lake appear milky turquoise. If the lake were completely clear, one would see it as just blue; but the suspended rock flour makes it opaque. This same phenomenon makes some Canadian and Swiss alpine lakes appear the signature blue-green of glacial lakes. On sunny afternoons, the contrast between the cobalt sky, white peaks and emerald water can be breathtaking. Clouds or sediment stirred by wind can mute the color, so calm mornings are favored by photographers.
Origins: The lakes occupy a broad cirque carved by the Ngozumpa Glacier, one of the largest glaciers outside the polar regions. Over the last few thousand years, retreating ice left behind moraine dams, filling depressions to create the lakes. The largest is Thonak (Thonak Tsho), with smaller lakes like Ngozumpa Tsho and Gyazumpa Tsho nearby. In 2007 the Gokyo region (and surrounding wetlands) were designated a Ramsar Wetland of International Importance due to its unique ecology and hydrology. Wildlife includes musk deer, bharal (blue sheep) and Himalayan tahr on slopes, and the lakes harbor some fish and amphibians adapted to cold. Reed beds along the shores provide habitat for snowcocks and waterfowl during the rare warm season.
Reaching Gokyo requires a multi-day trek: it is usually done as an extension of or alternative to the Everest Base Camp (EBC) trail. A common route from Lukla (2,840 m) takes about 7–10 days one-way via Namche Bazaar (3,440 m), ascending through Sagarmatha National Park. Climbers cross high passes like Renjo La (5,360 m) or Cho La (5,420 m) to reach the Gokyo Valley. With each higher camp, the air thins dramatically: trekkers go from forested rhododendron valleys to rocky moraines. This ascent carries real altitude risk. Trekking sources note that 30–40% of Gokyo trekkers experience some altitude sickness symptoms. Thus, planners stress gradual acclimatization: rest days at 3,800–4,000 m are standard, and climbers are warned that even young healthy people can develop headaches or nausea.
Packing List: Essential gear for Gokyo includes high-altitude boots, layered cold-weather clothing, and sun protection (the UV radiation above 5,000 m is intense). A sleeping bag rated to -10°C or better is necessary (nights can drop below -20°C). Travelers should carry altitude medications (e.g. acetazolamide, brand Diamox) and hydration salts. A reliable trekking pole helps on steep sections; oxygen bottles are optional but usually discouraged unless needed for emergency descent. For photography, a wide-angle lens and polarizer will capture vast panoramas and deepen the blue sky against snow. (Battery life is also short in cold, so carry spares or a solar charger.)
At Gokyo itself, the first and largest lake (Thonak Tsho, ~4,700 m) shimmers below the jagged peak of Cho Oyu. A hike to Gokyo Ri (5,357 m) – the rocky summit above the third lake – is rewarding: from there, one can often see four of the world’s five highest peaks in a single sweep. Early morning ascents are common, as clouds form by midday and often obscure the view. The tarns below Gokyo Ri take on even deeper turquoise at dawn, framed by pink clouds reflecting off Everest’s summit.
Compared to the standard Everest Base Camp route, the Gokyo trek has pros and cons. Pro: fewer people. Groups heading to EBC can number in the hundreds per day; by contrast, Gokyo’s route sees moderate traffic, even in high season. The Gokyo trail is more of a circuit, letting trekkers sample multiple high passes and villages. Many guides note that “Gokyo is quieter and more scenic”, since it circles the glacial headwaters. Con: it is longer and steeper. A typical EBC trek takes 11–12 days and ~106 km, whereas the Gokyo Lakes circuit can be 15–16 days and ~135 km. The extra days partly account for the high Cho La pass (5,420 m), which some guides rank as a strenuous glacier crossing. In practice, many trekkers do both by looping through Gokyo, then back over Renjo La to rejoin the EBC trail.
Indigenous Sherpa villages, Buddhist monasteries, mani walls and prayer flags pepper the route. Travelers observe Sherpa farmers tending yaks and reading prayer stones. Residents of the Khumjung and Marulung villages still regard the lakes as sacred: pilgrims bathe in them during the August Janai Purnima festival, seeking spiritual merit. Guides respect these practices; visitors are asked to wear modest clothing near monasteries and to drink gently (plastic bottles are discouraged; many lodges encourage refills of boiled water).
In practical terms, the trek requires permits: the Sagarmatha NP entry and a TIMS trekking permit. Teahouses along the route are basic but adequate (dorm bunks, shared restrooms). Accommodation at Gokyo village (the main settlement) is limited and often full at peak times; so late-arrivers may camp. Accommodation costs rise with altitude – roughly $5–15 per night for a basic twin room or bunk bed – but are still cheaper than Western standards. Hot meals (daal bhat, noodles, soups) are available daily. Winter and monsoon seasons are generally avoided: the best months are October–November and March–May, when trails are dry and skies are clearest. (Late spring also brings rhododendron blooms in lower valleys, adding color to the trek.)
“At altitudes above 4,000 m, almost every trekker feels the effects of thin air. In fact, ~30–40% of Gokyo route hikers develop at least mild altitude sickness. Careful acclimatization – resting every few days – is essential. But for those who make it, the reward is five sparkling lakes set against the highest peaks on Earth.”
In the rolling green countryside of Bohol (Central Visayas, Philippines) stand over a thousand small, conical hills arranged as if by cosmic design. From a high vantage these Chocolate Hills resemble giant perfectly shaped scoops of ice cream arrayed across 50 km². In the dry season, the grass that carpets the slopes dries to a deep brown, lending the hills their dessert-inspired name. It is the uniformity and symmetry of these limestone towers – up to 30–50 m tall each, with nearly identical steep sides – that dazzles geologists and visitors alike.
Despite their name, the hills are geological, not edible. They are made of marine limestone – the fossilized remains of coral and shell deposited millions of years ago, when the area was under a shallow sea. Multiple theories exist for how the hills took their form. The prevailing scientific explanation is karst weathering. Over the last 2 million years (Late Pliocene), tectonic uplift lifted these limestone layers above sea level. Once exposed to air and rain, the calcium carbonate rock dissolved unevenly. Rainwater (slightly acidic from CO₂) carved vertical joints, creating a pattern of funnels and sinkholes. Over time the tops of these funnels eroded at roughly the same rate, leaving a smooth, dome-like cone. In effect, one can view the Chocolate Hills as the remnants of an eroded plateau: where the rock was weakest it disappeared, and where it was strong it remained as a cone. Some studies describe them as haycock karst or “bubble” karst – an extremely rare form seen only in a few places worldwide.
Geologists can point to evidence in the rock: fossils of marine organisms and calcite layers within each hill. The hills have very uniform base width and height because they arose from the same limestone formation. The largest hill reaches about 120 m high, but most are 30–50 m tall (about 100–160 ft). The total count is often given as 1,268, but some surveys list up to 1,776 separate hills, depending on how smaller mounds are counted. The entire formation covers roughly 20 × 7 km in a horseshoe shape. Notably, this region lacks significant faulting or glacial activity; the uniformity suggests slow, uniform uplift rather than violent folding.
Historical Note: Local folklore offers poetic alternative explanations. One popular tale tells of a giant named Arogo who collected stones to throw at a rival; when Arogo died of grief at having lost his love, his weeping caused the stones on the ground to become the hills. Another variant speaks of two feuding giants hurling boulders until they became tired, leaving the hills behind. These legends – about tears of heartbroken giants or quarrelling spirits – are still told by Boholanos. They convey a sense that the hills are truly magical “gifts” from nature or gods, not just remnants of coral reefs.
The hills’ appearance changes dramatically with the seasons. In the rainy season (June–December), the grass and shrub cover is vibrant green. During the intense dry season (January–May, and especially February–April), the vegetation browns uniformly. From April through May, hundreds of tourists ascend the twin concrete viewing decks at Chocolate Hills Complex (in Carmen town) to see this color change: rolling fields of chocolate-brown domes under a clear sky. In practice, February to May is billed as the peak time for “chocolate” color. However, visiting when green can also be beautiful – the lush color accentuates the unique shapes.
Access and amenities are straightforward. The Chocolate Hills Complex has a visitor center, small museum, and platform where the hills spill out in all directions. Entrance fees are modest. A short hike (210 steps) leads to the main viewing deck. There is also an ATV tour service to explore the bases of the hills, and hiking trails for closer looks – though climbing the hills themselves is not permitted due to erosion concerns. In Bohol’s hot climate, mid-morning or late afternoon visits avoid the strongest sun. Guides often recommend visiting on a partly cloudy day: the diffused light can add contrast to the hills’ contours.
Nearby Bohol offers more context. The region’s karst valleys are pockmarked with caverns (e.g. Hinagdanan Cave, Mag-Aso Falls). Tarsier sanctuaries (for the tiny nocturnal primates) and old Spanish churches (Baclayon, Loboc) make for additional stops. The Chocolate Hills themselves are protected as a Natural Monument under Philippine law, and the government has sought UNESCO World Heritage status for their uniqueness. Conservation efforts focus on preventing quarrying or development on the hills. Locals treat them as a source of pride; folklore explains, for instance, that Tres Maria, the three smallest hills, are the resting place of three virgin sisters from one tale.
“Geologists say the Chocolate Hills were sculpted by limestone uplift and erosion; locals say they were born from a giant’s tears. In either case, the result is remarkable: 1,268 (or more) nearly identical cone hills covering tens of square kilometers. The hills wear a coat of green moss in the rains and turn dry-chocolate brown by April, hence their evocative name.”
On Flores Island, Indonesia, Mount Kelimutu is famed for its three summit crater lakes, each normally a different color – blue, green and red. Locals and volcanologists alike describe Kelimutu’s lakes as “living” in color, because each lake’s hue can shift suddenly and independently. Some have changed from blue to green or vice versa in a matter of months. When three stunning lakes share one volcano top and change hue arbitrarily, the effect is nothing short of mystical.
What drives these colors? In short, volcanic chemistry. Underground fumaroles inject gases (sulfur dioxide, hydrogen sulfide, carbon dioxide) into each lake. Those gases dissolve and react with minerals to alter the water’s oxidation-reduction balance. High sulfur content, for example, can turn water shades of green or yellow due to sulfuric deposits; high iron and other metals can make water red or brown (through oxidized iron and manganese compounds). Each lake has its own hidden plumbing to the volcano’s magmatic system, so a change in gas flux or rainfall can cause one lake to change color without affecting its neighbors. Scientific monitoring (though limited) has recorded rapid shifts – sometimes a lake’s pH swings wildly or a fumarole becomes more active, and the visible color swiftly follows. In 2016 alone, the Kelimutu lakes reportedly changed colors six times. However, it’s as much a matter of “when” as “if” – without continuous instruments, no scientist can predict exactly when each lake will change. Thus, visitors often approach the site with a sense of anticipation and wonder, knowing the sky-blue they see one week might turn hunter-green the next.
Every morning, guests trek to the summit (1,639 m elevation) before dawn. During the night, temperatures can drop below 5°C, and the trail through ferns and eucalyptus forest is softly lit by torchlight and lanterns. By 5–6 AM one emerges onto the rocky rim, where a chilly breeze greets the first rays. The three lakes lie below in separate craters. Commonly, Tiwu Ata Bupu (Lake of Old People) holds a blue color; Tiwu Ko’o Fai Nuwa Muri (Lake of Young Men and Maidens) a green (or pale blue); and Tiwu Ata Polo (Bewitched or Enchanted Lake) a red or dark maroon. In the photo above, for instance, we see the classic scheme.
Planning Note: Kelimutu’s lakes change unpredictably, so there is no “best time” for color – but clarity is best in the dry season. The June–November dry season tends to give clear dawn skies, whereas the December–March rains often bring mist and low clouds. If clear weather cooperates, sunrise lights each lake differently: the blue lake catches the first pale pink hues, while the eastern lakes blaze in warm orange sun. Wear layered clothing for pre-dawn chill, and expect very crowded viewpoints on any clear day.
The local Lio people have their own meaning for the lakes’ hues: the blue lake is believed to be the resting place of old people’s souls, the green lake for young people and maidens, and the red lake for souls deemed evil. Traditional ceremonies are sometimes held there: on each death anniversary a family may burn offerings by its assigned lake. In Lio belief, the three distinct colors reflect the three destinations of the departed – making Kelimutu not just a geological phenomenon, but a living part of the region’s spiritual landscape.
For hikers, reaching Kelimutu begins from the village of Ende (roughly 2 hours by road) or the tiny town of Moni (nearer trailhead). The final approach involves ~1–2 km of uphill trail through forest to the craters. There is an entrance fee to Kelimutu National Park (modest, under a few dollars). Several guesthouses in Moni cater to tourists, often offering guide services and packaged tours. Some visitors stay at Wologai (a nearby traditional village) for cultural immersion before climbing Kelimutu. The trek itself is moderate; children and seniors often make it given reasonable fitness.
Modern access is challenging: a small airport in Ende has limited flights, and the nearest major airport is in Bali. Once on Flores, road conditions to Kelimutu can be rough, especially in rain. However, the remarkable reward – three lakes behaving like chameleons in color – attracts visitors despite the effort. Field reports note that on days after heavy rain the eastern lakes (young and enchanted) often drain slightly and go cloudy, while the western (blue) lake may darken. Guides advise carrying rain gear and full water (there is none up top), and to wear sturdy shoes (rocks can be slippery with dew).
“Kelimutu’s trio of volcanic lakes is a rare case where you find blue, green, and red waters sharing one summit. The colors come from dissolved minerals and volcanic gases – iron and sulfur reactions make the green and red, for example. To the Lio people, each lake also holds souls: young, old, or wicked, matching their eerie hues.”
In the forests of Vietnam’s Phong Nha-Kẻ Bàng National Park lies a cave so vast it creates its own cloud forest inside. Hang Sơn Đoòng, discovered only in 1990 and surveyed in 2009, holds the title of world’s largest cave passage by volume. Measuring over 5 km long, 200 m high and 150 m wide in its main chamber, Son Doong is essentially an underground canyon. It defies normal cave expectations: daylight pours through collapsed roof sections (“dolines”), allowing trees to grow on sandy floors tens of meters beneath the surface. Hanging stalagmites the size of apartment buildings (up to 70–80 m tall) stand monumentally. Guides affectionately call one formation “the Hand of Dog” for its shape.
A British survey expedition’s diagram and photograph (2009) of Sơn Đoòng’s main chamber. At over 200 m tall, two Boeing 747 airliners could stand end-to-end under its roof. The cave’s sheer volume (≈38.5 million m³) makes it the largest known cave passage on Earth.
Discovery and Formation: Local hunter Hồ Khanh first stumbled upon a sinkhole entrance in 1990. He alerted a British caving team, who returned in 2009. They then explored and named the cave “Son Doong” (Vietnamese for “cave of mountains beyond Đoòng”). The cave developed over millions of years by slightly acidic water percolating through Permo-Carboniferous limestone. The flowing subterranean river gradually carved out the enormous passage. Scientists estimate Son Doong is between 2 and 5 million years old, making it geologically youthful, which partly explains its colossal size.
Unique Ecosystem: Where roof collapses allow sunlight, Son Doong has created a bizarre tropical cloud forest underground. At the base of collapse no. 1 and 2 (the two large skylights), soil has accumulated. Trees and vines grow beneath the open sky, reaching up toward the cave ceiling. Explorers have named these areas “Garden of Eden.” Bats, crickets, and a few species of blind fish or shrimp inhabit the damp caverns and pools. Once, Oxalis Adventure (the only licensed tour operator) reported an albino blind fish and cave shrimp discovered in Son Doong’s pools. Above the cave, the limestone is home to bats (it’s Vietnam’s largest bat cave), swiftlets whose nests are harvested elsewhere, and monkeys that glimpse the Sky inside at dusk. Rhacophorus frogs (gray treefrogs) have also been photographed on damp cave walls at night. Despite its grandeur, Son Doong’s interior climate is surprisingly stable – daytime cave temps are ~22–25°C (72–77°F), with high humidity.
Visiting Son Doong: Because of the fragility and exclusivity, Son Doong is not open to casual visitors. Tourists can only enter via an Oxalis-organized expedition (no independent trekking or day-trips). A permit cap is in place: about 1,000 visitors per year (it varies, but roughly this order) can go in. As a result, planning requires many months’ notice: Oxalis famously sells out each season. The standard tour is ~6 days and 5 nights, including camping inside the cave. The cost is steep – about $3,000 USD per person (2026 rates). This covers all logistics: park permits (~$600 included), local guides, porters (for gear), camping equipment, food, and safety gear (helmets, headlamps, ropes). Even jet-setting to Saigon and Hanoi, the cave tour is the single largest expense of a trip. But travelers willingly pay for the one-in-a-lifetime experience of sleeping under starlight in a cavern the size of a skyscraper.
Logistical details matter: permits open for booking usually around late summer for the next year’s season (which runs roughly January–August, since monsoon rains flood the cave outside that window). The physical demands are high: participants should be very fit. Typical days involve trekking up to 20 km on forest trails to reach cave entrances, rappelling 90 m down cave walls (“Great Wall of Vietnam”), wading through jungle pools, and carrying a small daypack. Oxalis requires all clients to undergo medical checks. Inside the cave, campsites are on sandy riverbanks; Oxalis provides all camp gear (tents, padded sleeping mats, biodegradable sleeping bags). Toilets in the cave are composting-latrine tents near camps. The expedition includes rest days in the caves (for acclimatization and exploration) and does not allow daylight exits until the trek’s end.
Comparison: Son Doong is sometimes called the seventh natural wonder of the world (though not an official title). It is physically massive even by global standards: in 2019 it was measured at ~9 km total length, which would surpass Vietnam’s own Paradise Cave (8.5 km) as the longest in the country. The largest cross-section of Son Doong is twice that of Malaysia’s Deer Cave, the next largest chamber by volume. By all metrics, it dwarfs typical tourist caves like Carlsbad Caverns or Waitomo; those might impress with stalactite arrays, but Son Doong’s scale is on another order. In effect, one day inside feels like exploring a subterranean mountain range with microclimates – a place as foreign as standing on another planet.
Alternatives: If Son Doong’s permit or price is unattainable, Phong Nha offers several other showcaves. Hang En (just outside Son Doong’s entrance) is the world’s third-largest cave chamber. Many Son Doong treks camp at Hang En on the first night. Paradise Cave (Hang Thien Duong) is a tourist-friendly 1.4 km concrete path through impressive stalactites; Tu Lan Cave systems offer wild caving adventures; and Hang Pygmy (Hang Mooc) is nearly as stunning but far cheaper. None match Son Doong’s grandeur, but they give a taste of this karst region’s magic.
“Son Doong is truly awe-inspiring. At 5+ km long, 200 m tall and 150 m wide in places, it contains forests, rivers and colossal formations that seem impossible underground. Only ~1,000 people a year see it, and expeditions cost ≈$3,000. Those limits ensure the cave remains pristine, but they also make the experience incredibly rare.”
On the winding Quây Sơn (Guichon) River straddling the Vietnam-China border lies a waterfall of almost unbelievable scale. Ban Gioc Falls (Vietnam) / Detian Falls (China) is actually one massive cataract split by karst islets into multiple tiers. In full flood it spans roughly 300 m across and drops about 30 m high. By volume and width, it is frequently cited as the largest transnational waterfall in Asia – the fourth largest on Earth after Iguazu, Victoria, and Niagara. Its roar and spray fill a bowl of limestone peaks, creating a majestic, misty scene.
Ban Gioc waterfall in Vietnam, in its lush green summer flow. On the border to the north, Detian falls on the Chinese side feed into the same cascades. The total drop is ~30 m, total width ~300 m (with both sides combined). This makes Ban Gioc/Detian one of Asia’s most immense waterfalls and the world’s fourth largest transnational falls.
The falls lie between Vietnam’s Cao Bằng province and China’s Guangxi region. In Chinese they are called Detian (德天), in Vietnamese Ban Gioc. Geographically, they surge over a fault step in karst bedrock, fed by monsoon rains. During late summer to early autumn (July–October), when Southeast Asia’s rainy season peaks, the falls swell to a thunderous wall of water. Rainfall upstream in the Chinese Yunnan highlands and Vietnamese hills channel into the Quây Sơn, causing the falls to flood dramatically. In dry season the flow shrinks – by December–May water can be surprisingly shallow, revealing stone steps. Many guides therefore recommend visiting September–November for maximum volume.
The waterfall’s scale reveals itself best when approached from multiple levels. On the Vietnamese side, visitors first see the falls at water level: a boat (bamboo raft) ride takes you to the base of the lower cascades. From there, rainbows often arch through the spray. Climbing a metal staircase leads to a cliffside view mid-fall, then a plateau offers a distant panorama including the iconic kárst towers. On the China side, wide concrete terraces allow a birds-eye perspective. The Chinese park (Detian Tourism Center) is more developed, with viewing platforms and border signage; Vietnam’s side (Ban Gioc) is wilder and closer to the water. Many visitors see both sides if cross-border travel (and visas) allow – indeed, a low-waterfall connects above the main drop, making it literally one waterfall divided politically.
Local Perspective: For the Tay and Nùng ethnic minorities who live here, Ban Gioc/Detian is more than a sight – it has spiritual and historical significance. Local stories say the falls were formed by a farmer and his cow (one legend has the cow jumping into water, creating the waterfall) and that it gave the villages fresh water and fish for centuries. Today, Chinese and Vietnamese tour brochures each claim the falls as their own heritage. However, guides emphasize peaceful cooperation: the waterfall belongs to both countries, and joint management treaties exist. At the site one can see soldiers and tourists from both sides mingling at the 53rd border marker.
For the traveler, logistics hinge on border rules. The Vietnam–China border crossing at Ban Gioc re-opened to tourism in the 2010s after decades of closure. Foreigners can now obtain day-visit visas to cross from Cao Bằng into Guangxi (or vice versa) to view the other side. From Hanoi, Ban Gioc is a roughly 350 km drive northeast (about 6–7 hours), via the highways through Hà Giang and Cao Bằng. From Nanning (China), it’s about 220 km (4–5 hours) via bus or car. Entrance fees are minimal (around a couple of dollars). A small park in Vietnam sells boating tickets (~30,000₫) to ride near the falls. Local homestays in Ban Gioc village and Cao Bằng city offer rustic lodging for $10–30 per night.
Photography tip: The Vietnamese Pác Bó site (home of Ho Chi Minh’s wartime base) is a few kilometers east, so many itineraries combine the two. But to truly capture Ban Gioc’s grandeur, one should time the visit for morning or late afternoon light. At midday the sun is overhead and rainsbows (if any) are directly above. With the limestone karsts backlit, either side’s falls can glow in gold or become silhouettes. The best colors often appear a couple of hours before sunset, when the west-side approach casts the eastern cliffs in shadow. Monsoon or winter mists, meanwhile, soften the edges and can create an ethereal, veil-like effect (though too much fog obscures detail).
“Ban Gioc/Detian is by far the largest waterfall in Asia’s tropical belt. Its total drop is ~30 m and combined width ~300 m, making it the fourth largest trans-boundary waterfall globally. In Vietnam, visitors climb to multiple tiers and even boat under the cascades; in China, terraces offer sweeping panoramas. No matter the side, the sight of such voluminous water amid karst peaks is unforgettable.”
Japan’s northern island of Hokkaido hosts hundreds of onsen (hot spring) resorts, many set in volcanic landscapes. The island’s geothermal wealth comes from its position on tectonic subduction zones (including the Kuril and Aleutian arcs). The result: dozens of active volcanoes and innumerable hot springs emerging year-round. In fact, Hokkaido boasts about 251 different onsen areas – the most of any prefecture in Japan. This means hot spring waters emerge virtually everywhere: steamy pools bubble up under snow, perch on mountain slopes, and even flow through city baths.
Noboribetsu Onsen’s “Hell Valley” (Jigokudani) is a classic Hokkaido scene of steaming fumaroles and mineral pools. Hokkaido, known as the “department store of hot springs,” has 9 different spring types in one area, and a total of 251 onsen regions island-wide.
The signature spring area is Noboribetsu (near Sapporo). Here, a broad volcanic crater (“Hell Valley”) spews plumes of steam amid fumaroles. Nine distinct water chemistries – from sulfur springs to saline and iron-rich waters – emerge from the valley. Visitors stroll through a moonscape of steam vents and demon statues, where the air always smells of sulfur and the ground underfoot bubbles with hot springs. The most famous pool, Oyunuma, has emerald-blue acidic waters that never freeze even in deep winter. Nearby footbaths and outdoor tubs allow visitors to warm up by the snowy paths. As a tourism slogan puts it, Noboribetsu is “a globally rare phenomenon” because of this diversity of springs.
Other notable sites in Hokkaido include:
Unlike tropical springs, Hokkaido’s onsen are especially atmospheric in winter. Heavy snows blanket the landscape, and outdoor rotenburo (open-air baths) let bathers soak while snowflakes fall. Steam rising from a hot tub against pale gray skies is a classic Japanese postcard image. Indeed, winter is a peak season for Hokkaido tourism (skiers and onsen-goers alike), whereas summer draws hikers to the volcanoes. Nonetheless, mild seasons have their own charm: spring cherry blossoms by a warm spring, or the crisp red foliage of autumn seen from a hot pool.
Cultural Note: Onsen etiquette is strict yet welcoming. Bathers must shower and thoroughly cleanse before entering any communal pool (using soap and rinsing away, often under a shower hose). Swimsuits are never worn in mixed or gender-segregated baths; instead, a small towel may be carried above water (never submerged). Tattoos historically have been taboo in onsen, so travelers with ink should check for tattoo-friendly baths or use private onsens. Some Hokkaido inns specifically advertise “all-tattoo welcome” baths, or offer private-family rooms for those concerned. Tips: many spring towns rent yukata (cotton bathrobes) and provide lockers. Always follow local bathhouse rules (e.g. no photography in shared areas).<span id=”local-perspective”></span>
The geology: Hokkaido’s mountains are the remnant of the collision of the Pacific and Okhotsk Plates. Many volcanoes there are Holocene-active. Hot spring water emerges from great depths, having been heated by magma. Each region’s water chemistry reflects the local mineralogy. For example, sulfur springs (like Noboribetsu’s) are light yellow or milky; iron springs (aka ochiai-yu) contain iron that can turn the bath orange-brown; alkaline springs (sodium bicarbonate) feel silky on skin and emerge clear. These differences fuel the mythology of healing. Indeed, Japanese science has tabulated dozens of therapeutic claims: from relief of muscle pain and fatigue to skin maladies (though of course any such medical benefit is best discussed with a doctor). Visiting signage often lists conditions “ameliorated” by each spring type (e.g. chloride spring for circulatory issues).
In Noboribetsu’s Hell Valley, the name “Jigokudani” literally means “Hell Valley,” reflecting the ominous steam vents. Visitors on paths see bubbling “mud pots” and sulfur deposits. The valley narrows into Oyunuma River (literally “Hot Spring Marsh”), where boiling pools turn pine needles to crisp upon contact. Despite the foreboding nickname, the entire area is a managed park with wooden walkways. Guides note that wild animals (e.g. Japanese macaques) occasionally stray close but typically keep distance from humans and overt geothermal vents.
Top Spring Experiences (Hokkaido):
“Noboribetsu is often called the ‘department store of hot springs’ because you can sample nine different spring types in one town. All told, Hokkaido claims 251 onsen areas – the most in Japan. Whether you bathe outdoors in snow or under cedar roofs, these steamy pools offer a uniquely Hokkaido way to connect with earth’s heat.”
The seven sites above vary widely in access, cost and effort. The table below summarizes key comparisons.
Wonder | Country(s) | Type | Height/Elev. | Best Season(s) | Difficulty | Cost (approx.) |
Zhangye Danxia | China (Gansu) | Painted sandstone hills | 1,500–1,900 m | Summer–autumn (Jun–Sep) | Easy–Moderate (walks) | Low (park fee ≈$12) |
Gokyo Lakes | Nepal | High-altitude lakes | 4,700–5,000 m | Autumn, Spring | High (10+ day trek) | Moderate ($200–800 incl. guides) |
Chocolate Hills | Philippines (Bohol) | Limestone cones | 30–50 m | Dry season (Feb–May) | Easy (drive + short hike) | Low (~$5 park fee) |
Kelimutu Lakes | Indonesia (Flores) | Volcanic crater lakes | 1,639 m (summit) | Dry season (Jun–Nov) | Moderate (1–2 km hike) | Low (~$3 park fee) |
Son Doong Cave | Vietnam | Gigantic cave canyon | Entrance ~800 m; cave >5,000 m length | Dry season (Jan–Aug) | Very High (6-day expedition) | Very High (~$3,000 tour) |
Ban Gioc/Detian Falls | Vietnam/China | Transboundary waterfalls | 30 m (drop) | Rainy season peak (Jun–Nov) | Easy (drive, short walks) | Low (<$5 entry/boat) |
Hokkaido Hot Springs | Japan | Geothermal spa (onsen) | Sea level to 1,300 m peaks | Winter & year-round (peak winter) | Easy (varies by resort) | Low–Moderate (public baths ~$5–10, ryokan $100+) |
Several insights emerge:
Itineraries & Combinations: Ambitious travelers might link these wonders regionally. For example: – Southeast Asia Circuit: Vietnam (Son Doong, Ban Gioc) + Philippines (Chocolate Hills) + Indonesia (Kelimutu) could be combined over weeks. Note that permits and gear vary widely: e.g. Son Doong needs advance booking, Kelimutu can be a side trip from Labuan Bajo/Ende, Ban Gioc day-trips from Hanoi.
– Himalayan Circuit: Zhangye Danxia (northwest China) can tie in with a China trip; Gokyo Lakes (Nepal) goes with either an Everest Base Camp trek or an Annapurna trek (with time to acclimatize).
– Northern Route: Hokkaido’s onsens can be their own itinerary (fly Tokyo–Sapporo or New Chitose), possibly combined with skiing or hiking in Daisetsuzan NP.
A more mathematical snippet summary:
Wonder | Easiest to Most Challenging | Cost Tier |
Easy: Chocolate Hills, Ban Gioc, Hokkaido Onsen (low/none) | Moderate: Zhangye, Kelimutu (small fees, easy access) | High: Son Doong ($3000) |
Challenging: Gokyo Lakes (altitude trek, permits) |
| Moderate: Gokyo Lakes (trekking costs) |
Ultimately, the “best” choice depends on priorities: if logistical ease is key, visit the Chocolate Hills, Kelimutu or Ban Gioc. If you want remote adventure at any price, Son Doong awaits. For an epic trek with alpine views, Gokyo delivers. Hokkaido’s springs reward any schedule.
Key considerations include timing, budgets, gear, health and visas. Below are consolidated tips applicable across these seven wonders:
Country | Visa Needed | Length | Notes |
China | Yes | 30–90d | Required for Detian side; get in advance |
Vietnam | Yes/E-visa | 30–90d | E-visa online available; stamping on arrival |
Nepal | Visa on Arr. | 30d | Obtain at Kathmandu or Pokhara international |
Philippines | Visa-free | 30d | Extendable to 59d via airport |
Indonesia | Visa-free/VOA | 30d | Flores entry via Ende; VOA available |
Japan | Visa-free | 90d | Entry via Tokyo or Sapporo |
Q: What causes the Rainbow Mountains’ stripes and are they real?
A: They are completely natural, formed by layers of colored sandstone and minerals deposited 100+ million years ago. After tectonic uplift and erosion, iron, chlorite and other minerals oxidized to produce the red, yellow, green and other bands. (In fact, per geology sources, one can walk right up the public platforms and see the layers – they’re not painted or fake.)
Q: Can I walk on the Rainbow Mountains?
A: No. To protect the fragile surface, visitors must stay on designated paths and viewing decks. The park’s boardwalks allow close views of each slope. Straying off path is prohibited and penalized, as it can cause erosion.
Q: What causes the Kelimutu lakes to change color?
A: Chemical reactions between volcanic gases (like sulfur dioxide) and minerals in each lake produce changing hues. Each lake’s spring source and acidity vary, so one lake can shift from blue to green while its neighbor stays the same. Rainfall and oxidation-reduction balance also play roles.
Q: How many Chocolate Hills are there and why “chocolate”?
A: Counts vary by survey, but about 1,260–1,776 distinct hills have been identified across 50 km². They turn brown in the dry season (like chocolate) – until then they are verdant green. The name comes from this seasonal look. Geologically they’re limestone cones, not anything edible.
Q: How many people can visit Son Doong Cave each year?
A: Due to park caps, around 1,000–1,200 people per year are allowed on Son Doong expeditions. This cap (imposed for conservation) is why bookings often sell out months in advance.
Q: Is it possible to visit Son Doong without a guided tour?
A: No. Son Doong is inside a national park and is only accessible via authorized Oxalis expeditions. Independent trekking or “guerilla” visits are prohibited. If Son Doong is full, consider Hang En (the huge cave just outside Doong’s entrance) which Oxalis also includes in its tours, or other park caves (Paradise, Phong Nha Cave) that have regular day tours.
Q: Which is easier: trekking to Gokyo Lakes or to Everest Base Camp?
A: Gokyo is generally considered longer and harder. The Base Camp trek (ending at 5,364 m) takes ~11–12 days, whereas the Gokyo circuit can be 15–16 days with higher passes (Cho La at 5,420 m). Both involve similar altitudes, but Gokyo’s added distance and second pass make it more strenuous. However, Gokyo has fewer crowds and a more varied route.
Q: Are these wonders safe and easy to visit?
A: All are safe if properly prepared and guided. Lowland sites (Zhangye, Chocolate Hills, Ban Gioc, Hokkaido Onsen) have minimal risk besides normal travel hassles. High places (Gokyo, Kelimutu) require acclimatization and a guide for safety in mountains or volcanoes. Son Doong is the most restrictive: only experienced guides go in. In every case, listen to local advice – check weather, hire reputable guides, and have travel insurance.
Q: Which of these places is easiest for families/children?
A: The Chocolate Hills, Zhangye Danxia, and Ban Gioc Falls require only short walks (or even just viewing platforms), so they’re friendly for families. Kelimutu can be done with school-age kids (a steeper but short hike). Gokyo is best for teenagers or adults with trekking experience (altitude is a challenge). Son Doong is only for adults or older teens and with prior wilderness experience. Hokkaido onsen are family-friendly (many have mixed-gender baths and play areas), but check individual bath rules on children.
These seven Asian landscapes are more than pretty pictures; each embodies deep threads of Earth’s history. The Rainbow Mountains record 24 million years of sedimentation and mountain-building. Gokyo’s glacial lakes reflect the ongoing dance of ice and rock under Himalayan skies. The Chocolate Hills challenge our understanding of how uniform geology and erosion can conspire to create mathematical regularity on a natural terrain. Kelimutu’s shifting lakes remind us that our planet’s surface is alive – a cauldron of chemistry sensitive to unseen forces. Son Doong invites humility before the vastness of natural cavities, showing that uncharted wonders still lurk beneath the forest. Ban Gioc is both a boundary and a bridge – a shared marvel between nations. Hokkaido’s onsen tie human culture to deep geological heat, a daily reminder that the Earth’s warmth reaches our surface to soothe and shape life.
Each site also carries an ethical lesson. These wonders emerge from millions of years of processes, while human history in the area is but a blink. As visitors, we tread lightly on such time-worn art. Conservation efforts – whether UNESCO protections, permit limits, or cultural stewardship – seek to keep these places wild even as more travelers yearn to see them. Our exploration should honor both the science (no graffiti on rocks, no trash) and the soul (respecting local legends and practices) of each site.
Ultimately, these landscapes remind us of how small and connected we are. They are “impossible” only to our untrained eye; geology explains them. But they also spark wonder, imagination, and storytelling. Walking among them, one glimpses nature’s power and patience. Whether viewed through a scientist’s lens or a poet’s, they educate and inspire, bending the boundaries between Earth and sky, past and present.
