This almost perfectly circular sinkhole is about 300 m (984 ft) across and 125 m (410 ft) deep, making it one of the world’s largest marine sinkholes. Centred in the Belize Barrier Reef Reserve System (a UNESCO World Heritage site), the Blue Hole appears as a deep-blue eye in satellite imagery (as shown above) surrounded by lighter turquoise reefs and shallow sand flats. It was formed by the collapse of an ancient limestone cave, left underwater when Ice-Age sea levels rose. This feature continues to captivate scientists and travelers alike, with its towering stalactite structures, unique ecology, and centuries of exploration history.
The Great Blue Hole began as a series of dry caves during the last glacial period, when sea levels were much lower. Over 153,000 to 15,000 years ago, these caverns formed dripstone (stalactite and stalagmite) formations, as evidenced by submersed stalactites now uncovered at depths around 130–135 feet. As post-glacial sea levels rose, the caves flooded and eventually collapsed, leaving the vertical-walled chasm seen today. Geologists identify ledges on the Blue Hole walls at about 21 m, 49 m, and 91 m depths – reminders of past sea levels. Today the Blue Hole plunges a breathtaking 407 feet (124 meters) to an anoxic bottom. A layer of toxic hydrogen sulfide (“sulfide layer”) usually sits around 90 m deep, below which no oxygen or life exists.
Geological surveys confirm the Blue Hole’s uniqueness. NASA Earth Observatory data note that the limestone ring surrounding the hole actually breaches the ocean surface at low tide in places, contributing to the lighter reef colors around it. Remarkably, from space the Blue Hole is clearly visible as a dark blue circle – its high contrast against the reef and shallow sands makes it an unmistakable landmark. Indeed, NASA calls the Blue Hole “the world’s largest feature of its kind” and emphasizes its place within the broader reef system.
The Great Blue Hole has long intrigued explorers. British naturalist Charles Darwin saw Belize’s barrier reef (including the area of the Blue Hole) during his 1832 voyage, later calling it “the most remarkable reef in the West Indies”. The Blue Hole itself entered popular consciousness in modern times thanks to ocean explorer Jacques Cousteau. In 1971, Cousteau brought his ship Calypso to Belize’s Lighthouse Reef and declared the Blue Hole one of the world’s top five scuba dive sites. He filmed inside the hole, introducing it to a global audience. Scientists aboard that expedition confirmed the karst origins of the sinkhole (the four ledges and submerged stalactites), and even hypothesized that the entire plateau might have tilted slightly as the hole formed.
In later decades the Blue Hole continued to draw researchers. A 1997 scientific dive effort collected core samples from the seafloor, requiring cave-diving and mixed-gas expertise. More recently, a high-profile Discovery Channel broadcast (December 2018) brought unprecedented attention. In late 2018, NatGeo Explorer Erika Bergman led a team on twin submarines that descended through the full 407-foot depth of the Blue Hole. Joined by Sir Richard Branson and oceanographer Fabien Cousteau (Jacques’ grandson), the crew made 22 dives over two weeks, mapping the interior and capturing live footage on a global broadcast.
This mission produced a complete 360º sonar map of the hole and revealed its secrets – including massive stalactites still hanging 400+ feet deep and the graveyard of two lost divers. (The team respectfully reported two discovered skeletons to authorities but, honoring their peaceful resting place, did not recover them.) The expedition’s successes were hailed as historic, and they spotlighted Belize’s efforts in ocean conservation.
Jacques Cousteau’s 1971 dive set the tone for Belize’s underwater tourism boom. He reportedly declared the Great Blue Hole “one of the top 5 scuba diving sites on earth”. Cousteau’s film reels showed staggering views of the circular opening and its inner caves, inspiring generations of divers to add it to their bucket lists. Scientific analysis at the time already verified the hole’s multi-stage karst formation. Since Cousteau’s visit, thousands of divers have made the pilgrimage, and the hole has become emblematic of Belize’s Barrier Reef.
The 2018 NatGeo/Discovery mission (a modern deep-ocean exploration) was led by pilot Erika Bergman of Aquatica Submarines, alongside Branson and Cousteau Jr.. Over 22 dives, the team discovered unprecedented geological and human artifacts. Branson noted spotting “giant stalactites on rock walls” deep below. They also documented marine life up to the H₂S layer: tropical fish, turtles, even reef sharks swam in the upper 90 meters. Meanwhile, Bergman and crew confirmed darker realities: a thick, toxic hydrogen sulfide layer at ~90 m creates an oxygen-free zone below, where only shellfish carcasses lie. As Branson put it, seeing these geologic markers convinced him of climate change’s impact on sea levels – a powerful “magic of the Blue Hole” moment.
Visiting the Great Blue Hole requires some planning, as it is 43 nautical miles from Belize’s mainland coast.
✈️ Flights & Travel — Major Airlines to Belize City (BZE)
| Origin (City) | Airline(s) | Flight Time | Notes |
|---|---|---|---|
| Miami (MIA) | American (AA) | ~2h | Daily service |
| Dallas (DFW) | American (AA) | ~2h 50m | Non-stop |
| Charlotte (CLT) | American (AA) | ~3h 24m | Seasonal |
| Houston (IAH / HOU) | United, Southwest | ~2h 20m | Year-round |
| Chicago (ORD) | United (UA) | ~4h 15m | Non-stop (seasonal frequency may vary) |
| New York (JFK) | JetBlue (B6) | ~4h 45m | Non-stop |
| Toronto (YYZ) | WestJet, Air Canada | ~4h 15m | Seasonal (Nov–May peak) |
Scuba diving the Great Blue Hole is an adrenaline-packed experience. Depth drops off precipitously – the walls fall from 40 feet down to 130 feet where stalactites loom. Dive masters typically send divers down to 130–135 ft for a short, purposeful dive (often only 7–10 minutes bottom time) to view the stalactite formations. Divers then ascend slowly with mandatory decompression stops (usually at 15 ft) before surfacing. Many dive boats combine this with two additional shallower dives (40–60 ft) on nearby walls (Half Moon Caye Wall, The Aquarium at Long Caye) to enjoy more marine life.
For many visitors, seeing the Great Blue Hole from above is unforgettable. Light aircraft and helicopter tours lift off from Ambergris Caye or Belize City early in the morning for the best view. These flights typically head southeast over the Barrier Reef, providing sweeping vistas of colorful atolls, then circle the Blue Hole for several passes. An eight-seater puddle jumper (Cessna) or 4-person helicopter can both get you there – just book in advance, especially in high season.
Photographers should aim for mid-morning or late afternoon light. Around noon, the sun illuminates the sinkhole’s blue water, enhancing color contrast. (However, direct overhead sun can be harsh; early morning light gives warmer tones to the reef.) The Great Blue Hole presents striking patterns: the dark central core, the surrounding bright ring of reef, and specks of white sand. In aerial photos, Half Moon Caye (the small green island 12 miles to the southeast) often appears just outside the blue circle. Capturing both is popular: framing the Blue Hole with birdlife or boats adds scale.
Drone & Legal Notes: Flying drones around the Great Blue Hole requires care. Drone photography from an aircraft is banned (safety risk). To fly a drone near the hole, one must launch from a boat at the reef’s edge and obtain permits weeks in advance. Belize’s Civil Aviation and Marine Parks authorities require registration and a 4–8 week approval process for drone flights. Unauthorized drones risk confiscation and fines (~US$1,000). In practice, most visitors enjoy photography from fixed-wing or helicopter tours rather than attempting drone shots. Safety Tip: Keep camera straps secure in flight – turbulence can be unpredictable over the open Caribbean.
From above, the Blue Hole’s perfect circle and surrounding reef are unmistakable. When shooting from a plane, sit on the side facing the reef for the best color – on the left side if coming from Belize City. Use a polarizing filter to cut glare from the water.
The Great Blue Hole sits within one of the most diverse marine ecosystems on Earth – the Belize Barrier Reef Reserve System (BBRRS). This UNESCO World Heritage site (inscribed in 1996) spans 185 miles of reef and includes several atolls (Lighthouse, Turneffe, Glover’s), sand cays and mangroves. UNESCO emphasizes the site’s outstanding natural value and vulnerability: more than half of Belize’s protected areas lie in this system, making it “the premier natural landscape” for conservation. Charles Darwin’s 1840 observation—calling it “the most remarkable reef in the West Indies”—underscores its long-recognized importance.
Marine life here is rich. The Belize Barrier Reef is home to 500+ fish species and 65+ species of hard coral. Famous inhabitants include hawksbill and green turtles, nurse sharks, stingrays, and the occasional manatee or barracuda. Threatened species protected in the region include the West Indian manatee, American crocodile, and all local sea turtles. Half Moon Caye is especially notable for wildlife: its littoral forest supports one of the Caribbean’s only breeding colonies of red-footed boobies, and its beaches are nesting grounds for endangered loggerhead, hawksbill and green turtles. Glover’s Reef is a critical marine reserve with some 850 patch reefs and key spawning sites for groupers and other fish.
On World Oceans Day 2023 Belize launched a playful social media campaign called “Reef With A Beef”. This tongue-in-cheek campaign personifies the reef as demanding action on pollution. Using Twitter and Instagram (@ReefWithABeef), it “trash talks” global polluters to raise awareness about ocean health. The Belize Tourism Board highlights that nearly half the country is under protected status, and the reef extends 185 miles with hundreds of coral and fish species. These efforts – from marine reserves to grassroots programs – underscore Belize’s passion for reef conservation.
Whether you’re building a Belize trip around the Blue Hole or adding it to a longer journey, here are some planning pointers:
Q: How deep is the Great Blue Hole?
A: The sinkhole is about 407 feet (124 meters) deep at its deepest point. Divers usually reach 130–135 ft (40 m) to see the stalactites.
Q: Who made the Great Blue Hole famous?
A: Jacques Cousteau popularized it in 1971, calling it a top-five dive site. More recently, a 2018 live broadcast featuring Sir Richard Branson, Fabien Cousteau, and Erika Bergman brought it to global attention.
Q: What certifications do I need to dive there?
A: Divers should have an Advanced Open Water certification or equivalent deep-diving training. Many dive shops require a logged dive to 80+ feet within the past 6 months. Nitrox is recommended for safety.
Q: Can I snorkel the Great Blue Hole?
A: You can swim on the surface, but snorkeling only the shallow rim won’t reveal the cave structures. For snorkeling, most tours include shallow reef dives around Lighthouse Reef or Half Moon Caye to see coral and fish. If snorkel is your goal, inform the operator to adjust the itinerary.
Q: How do I get there?
A: Fly into Belize City (BZE). Then transfer to Ambergris Caye or Caye Caulker by taxi or plane. From there, speedboat tours (90–120 min) or chopper flights go to the Blue Hole. Some tours start directly from Belize City or South Ambergris.
Q: Are tours expensive?
A: Blue Hole dive/snorkel trips typically range US$250–400 per person, including boat transit, gear, guides, lunch, and two additional reef dives. Helicopter tours run ~$250–350 for 30–45 min flights. Marine park fees ($40) are extra.
Q: What wildlife will I see?
A: Inside the sinkhole (beyond ~300 ft) life is scarce due to low oxygen. However, near the edges you might spot Caribbean reef sharks, nurse sharks, turtles, eagle rays, and plentiful tropical fish. Booby birds and frigatebirds nesting at Half Moon Caye are a highlight above water.
Q: Is it safe to visit in hurricane season?
A: The Blue Hole is accessible year-round, but June–October is hurricane season. Sea conditions can be rough. Most operators prefer Nov–May (dry season) for calm weather. Always check weather and book with a reputable tour operator that can cancel if needed.
Q: Do I need a visa to visit Belize?
A: Many travelers (US, Canada, EU, etc.) do not need a visa for stays under 30 days. Check Belize’s immigration website for your nationality. Passports must be valid 6 months beyond your stay.
Q: How long does sand filling take?
A: Scientists estimate that sand slowly erodes the Blue Hole. Some describe it as an “underwater hourglass” – each day tiny sandfalls erode the rim. Eventually (likely many millennia), it could fill, but that’s on geological timescales.
Q: What’s the “Reef with a Beef” campaign?
A: It’s a Belize Tourism Board campaign launched in June 2023 to raise awareness of ocean pollution. The reef (as an online persona) “trash talks” polluters on social media. It highlights Belize’s conservation successes (50% of land protected, UNESCO reef, etc.) to inspire global change.
