To get across island groupings, you must essentially fly (or sail).
Renting motorcycles, scooters, and bicycles is possible on Tongatapu, Vava’u, and Ha’apai. You may rent a vehicle on Tongatapu. Taxis are also available. Tongatapu, Teta Excursions, and Toni’s Guest House provide day tours of all the major tourist attractions on the main island. The speed limit is typically 40km/h, which is strictly enforced by local drivers. Before you drive, you must purchase a local Tongan driving license in addition to your current license (25 pa’anga). The roads in and around Nuku’alofa are excellent, although they degrade as you drive farther out from the town and south. Most vehicles in Tonga are in poor condition, having been maintained on a shoestring budget and kept together by a mixture of ‘Western Union’ stickers and prayer. The low speed limit contributes to fewer accidents. There are buses from Nuku’alofa to different locations on Tongatapu, however there are no schedules.