Top 10 Dive Sites in Thailand
Thailand has built one of Asia's most accessible and rewarding dive industries on two coasts that face different oceans and operate on opposite seasons. The Andaman Sea, washing the west coast from Phuket to Koh Lanta, offers the country's most dramatic diving — seamounts rising from 40 metres, pinnacles swept by current, and visits from whale sharks and manta rays. The Gulf of Thailand, on the east coast, is gentler and more forgiving, with shallow reefs ideal for training and famous aggregations of seasonal species. Between the two coasts, Thailand accommodates a beginner learning finning technique in a sheltered bay and a seasoned diver navigating a submerged pinnacle in a three-knot current. Open the map to explore dive sites across both coasts.
1. Richelieu Rock, Similan Islands area
Richelieu Rock is a horseshoe-shaped limestone pinnacle located in the Surin Islands Marine National Park, about 18 kilometres from the nearest landmass. It breaks the surface at low tide and descends to around 35 metres all around its circumference. The density of marine life at Richelieu is extraordinary even by Thai standards: the pinnacle is smothered in sea anemones housing multiple clownfish species, soft coral in deep crimson and orange, and enormous nudibranchs rarely seen elsewhere. Whale sharks visit regularly between February and April. The current runs hard around the outer shoulders of the rock and beginners should stick to the protected interior walls. Advanced Open Water recommended.
2. Koh Bon Pinnacle, Similan Islands
Koh Bon is a small island at the northern end of the Similan Island chain, but the dive site is not the island itself but rather the submerged ridge extending southwest from its southern tip. The ridge drops from around 12 metres to beyond 30 metres, and the main attraction is manta ray season: from December through April, large oceanic manta rays circle the pinnacle to be cleaned and feed on the plankton-rich current. Divemasters typically anchor divers at around 20 metres on the reef crest and the mantas pass at arms' reach. Outside manta season, leopard sharks rest on the sandy bottom. Advanced Open Water; drift experience helpful.
3. Similan Islands, Dive Sites 7–9
The northern islands of the Similan Marine National Park — particularly No. 7, No. 8, and No. 9 — contain the archipelago's most varied diving. The east sides are calm with hard-coral gardens beginning at three metres; the west sides have famous boulder formations — East of Eden, Christmas Point, Fantasea Reef — where granite boulders have collapsed into chaos, creating swim-throughs, arches, and canyons down to 30 metres. Hawksbill turtles are common nesters. The Similan Islands are accessible by liveaboard from Khao Lak or by day trip from Phuket; the park is closed May through October. Open Water divers on the east sides; Advanced for the west-side boulders and currents.
4. Hin Daeng, Koh Lanta
Hin Daeng — Red Rock — is a submerged pinnacle in the Koh Lanta Marine National Park, around two hours from the nearest dive centre by speedboat. The top of the pinnacle sits at around eight metres and the walls drop vertically to beyond 40 metres, carpeted in enormous red sea fans — the largest concentration of Melithaea fan corals in Thailand. Grey reef sharks, silvertip sharks, and leopard sharks are regular visitors; whale shark encounters are not uncommon between November and April. The current here can exceed three knots and the site commands respect. The adjacent Hin Muang (Purple Rock), where the soft coral turns entire walls violet, is often dived on the same trip. Advanced certification required.
5. Sail Rock, Gulf of Thailand
Sail Rock, locally called Hin Bai, is a granite pinnacle rising from 40 metres in the Gulf of Thailand between Koh Samui and Koh Phangan. A hollow chimney through the centre of the rock, open at 5 and 18 metres, allows divers to swim inside the pinnacle itself — one of the most photographed features in Thai diving. Chevron barracuda school in enormous spirals around the rock's upper section. Whale sharks visit Sail Rock reliably between March and May, and individual fish have been identified and tracked over multiple seasons by local researchers. The site is accessible year-round from Koh Tao (90 minutes) or Koh Phangan. Advanced Open Water recommended for the deeper sections.
6. Chumphon Pinnacle, Koh Tao
Chumphon Pinnacle lies about 14 kilometres northwest of Koh Tao at depths of 14 to 36 metres. Three granite pinnacles cluster together in open ocean, and the resident population of large grouper, including giant grouper exceeding a metre in length, is exceptional. Schools of bigeye jacks circle the pinnacle tips constantly. Whale sharks are sighted here more regularly than at any other site accessible from Koh Tao, particularly between April and June. The current runs hard on both the ebb and flood, and the pinnacle is a genuine Advanced-level dive; the top section around 14 metres is accessible to confident Open Water divers in calm conditions.
7. Southwest Pinnacle, Koh Tao
Southwest Pinnacle is the most reliably productive site in the Koh Tao area for mixed species encounters. The main pinnacle rises from 33 metres to around 6 metres, and several smaller satellite towers cluster nearby. The walls are draped in wire coral and the deeper sections regularly produce bull sharks and grey reef sharks between October and February. Bull shark encounters here are generally passive — the sharks circle at depth, ignoring divers — but appropriate respect and a calm hovering technique is essential. The site is Advanced Open Water level due to depth and occasional strong current.
8. Koh Tao South, Japanese Gardens
Japanese Gardens is Koh Tao's most famous gentle site, a broad shallow reef at two to twelve metres extending off the southern end of the island near the Thai Thani resort headland. The coral coverage is dense despite the site's popularity, with large fields of staghorn and plate coral, and the fish life includes butterfly fish, angel fish, and the ever-present Koh Tao cleaning stations where surgeonfish and wrasse queue for service. It is an outstanding training site and one of the best night-dive options in the Gulf of Thailand. Open Water and student divers thrive here; experienced divers use it for skills practice or guided macro sessions at night.
9. Hin Muang, Koh Lanta
While Hin Daeng draws the shark-seekers, Hin Muang is the site that photographers remember longest. The pinnacle rises from 65 metres (its full depth is unknown) to around 14 metres below the surface, and the upper 20 metres of wall are coated in soft purple Dendronephthya coral so densely packed that the rock beneath is invisible. The site hosts one of the highest densities of large gorgonian fans in Thailand, and the resident eagle ray population is unusually tolerant of divers. Currents at Hin Muang rival those at Hin Daeng and conditions can deteriorate rapidly in the afternoon; morning dives are strongly recommended. Advanced certification and current-diving experience required.
10. Phi Phi Islands, Viking Cave
The caves and walls around the Phi Phi Archipelago — particularly the Viking Cave wall on the north shore of Phi Phi Leh — are accessible from Phuket and Krabi and see significant day-trip traffic, but the wall diving below the tourist boats is genuinely excellent. The wall drops from three metres to around 25 metres with horizontal cracks sheltering large moray eels and grouper. The corner of Viking Cave produces current when the tide moves, pushing in baitfish and the trevally and barracuda that hunt them. Leopard sharks are a year-round resident of the sandy bottom between the cave and the neighbouring wall section. Open Water divers; strong current sections are Advanced level.
Planning Your Thailand Dive Trip
The Andaman Sea operates from October to May; the national parks at Similan and Surin close in May and reopen in October. The Gulf of Thailand (Koh Tao, Koh Samui, Koh Phangan) dives year-round with a brief rough period in October and November. Liveaboards depart Khao Lak for the Similan and Surin Islands between November and April; week-long Andaman itineraries are the most cost-effective way to hit Hin Daeng, Hin Muang, and Richelieu Rock in a single trip. Koh Tao is the cheapest place in Southeast Asia to complete PADI Open Water certification. Operators including Big Blue, Khao Lak Fun Divers, and Chumphon Diving Center maintain strong safety records. Open the map to find dive centres and sites across Thailand.