Thailand

Best overall months to dive: Feb–Apr

Thailand has two dive coasts on offset monsoon clocks. The Andaman side — the Similan Islands, the Surin Islands, the southern pinnacles of Hin Daeng and Hin Muang, the reefs around Phi Phi and Koh Lanta, and remote Koh Lipe in the far south near the Malaysia border — runs roughly mid-October to mid-May, with granite topography, mantas and seasonal whale sharks; several of its national parks close through the monsoon. The Gulf side splits in two: Koh Tao in the west dives year-round and is one of the world's busiest scuba-training hubs, while Koh Chang in the eastern Gulf runs its own November-to-April season around the HTMS Chang wreck, with warmer water and more modest visibility. Because the coasts are offset, something is in season for most of the year.

Dive regions