Thailand
Ko Pha Ngan is an island in the Gulf of Thailand whose dive operators run trips to a cluster of nearby sites, most notably Sail Rock, one of the most highly regarded dive sites in the Gulf.
Diving from Ko Pha Ngan centers on Sail Rock (Hin Bai), a granite pinnacle located between Koh Phangan and Koh Tao that rises above the surface and descends past 20 meters, known for its vertical 'Chimney' swim-through and for large schooling fish, with whale sharks occasionally sighted. Closer to the island itself, local dive centers also run trips to sites such as Koh Ma and Haad Salad, which offer shallower coral reef diving suited to less experienced divers.