Top 10 Dive Sites in Cambodia
Cambodia's dive industry is centred on the Gulf of Thailand coast — the strip of islands and mainland coast accessible from the rapidly developing port town of Sihanoukville. The diving here is not world-class by the standards of the Coral Triangle or the Red Sea, but it offers something valuable: warm water (27–30°C year-round), good marine life on the quieter sites, and a low-pressure, underdeveloped atmosphere that is increasingly rare in Southeast Asian diving. The visibility varies considerably — 5 metres on a rough day near the mainland, up to 20 metres on the outer islands in good conditions — and the depth is generally modest, rarely exceeding 25 metres on the recreational sites. Cambodia's dive industry is young and expanding, and the islands of Koh Rong and Koh Tang in particular have sites that will reward patient, attentive divers.
1. Koh Rong, Gulf of Thailand
Koh Rong is the largest island in the Cambodian archipelago and the most developed for tourism, but parts of its coastline remain quiet enough to support genuinely good diving. The western and southern shores have the clearest water, with reef systems descending to around 18 metres before giving way to sandy bottom. Hard coral coverage is variable — the inshore reefs have suffered from some bleaching and boat anchor damage — but the outer points of the island show much better coral health. Reef fish density is good: parrotfish, surgeonfish, and various snapper and grouper species are reliably present. Whale sharks have been sighted in the channel between Koh Rong and the mainland during certain seasons, usually around May and June when plankton blooms are heavy.
2. Koh Tang, Western Cambodia
Koh Tang gained a degree of historical notoriety as the site of the last official battle of the Vietnam War — the 1975 Mayagüez incident — but for divers it is simply one of Cambodia's better outer islands. Its greater distance from the mainland (about 45 kilometres south of Sihanoukville) translates to cleaner water, better visibility, and reefs that have seen less anchor and fishing damage than the closer islands. The south and east sides of the island carry the most interesting coral, with depths to 22 metres and good coverage of table corals and brain corals on the upper sections. Blacktip reef sharks are occasionally sighted around the rocky points. The island is rarely visited by dive boats from Sihanoukville because of the distance involved; those who make the trip generally find it worthwhile.
3. Koh Prins, Near Sihanoukville
Koh Prins is one of the closer outer islands to Sihanoukville, making it a practical destination for day trips without the fuel costs and time investment of the more distant sites. The reefs here are patchy — some sections have seen better days — but there are areas of good coral health on the northern and western exposures. Nudibranchs are well represented here, and the site is known among local operators as a reliable macro dive. Frogfish have been found on the rubble sections between coral heads. Depths are shallow throughout, rarely exceeding 15 metres, which keeps the site appropriate for Open Water divers. The sheltered bays also suit beginner divers on days when swell affects the more exposed sites.
4. Condor Reef, Offshore Site
Condor Reef is an isolated submerged reef system in the outer Gulf of Thailand, rarely dived due to its distance from the main Sihanoukville operating base. Operators who run day trips or multi-day excursions here report consistently better visibility than the inshore sites (15 to 20 metres is typical) and more intact coral structures. The depth tops out at around 20 metres on the reef crest. Larger marine life — trevally, barracuda schools, and occasional rays — appears here in greater numbers than on the busier closer sites. If you are serious about Cambodian diving and prepared to spend time on a boat to reach quality, Condor Reef is the clearest argument for doing so.
5. Koh Rong Samloem, South Side
Koh Rong Samloem is the quieter southern sister island to Koh Rong, less developed and seeing significantly lower boat traffic. The diving on its southern and western shores benefits directly from this. Coral coverage is better than on many comparable Cambodian sites, and the lack of anchor damage on the quieter mooring points is visible. The marine protected area status of parts of the island has helped maintain fish populations. Depths range from 5 to 20 metres on the main dive sites. Seahorses are reliably found in the seagrass beds near the shore. Night dives from the beach are accessible and productive — octopus, flamboyant cuttlefish, and various small crustaceans are active after dark.
6. Koh Sdach Archipelago, Koh Kong Province
The Koh Sdach island group in the northwest of Cambodia's coast near the Thai border sees minimal dive traffic, which in this case is the point. The handful of operators running trips here report pristine water quality, healthy soft coral on the rocky points, and excellent shark sightings — blacktip and whitetip reef sharks are consistently present around the outer islands. Infrastructure is minimal and the dive industry here is genuinely developing rather than mature. Divers who travel independently to this area will need to arrange logistics carefully and have realistic expectations about equipment availability, but the reward is a sense of exploration that has largely been priced out of the more popular Southeast Asian destinations.
7. Bamboo Island (Koh Pos), South of Sihanoukville
Bamboo Island is one of the smaller islands accessible on a half-day boat trip from Sihanoukville. The diving is modest — depths to around 15 metres, variable coral coverage — but the fish life around the island's rocky edges is reliable and the site is appropriate for newly certified divers or for a relaxed second dive on a day trip that has started at a better site. Moray eels and scorpionfish are common on the rocky substrate. The island itself has a beach that makes it a natural stopping point for surface intervals.
8. Koh Ta Kiev, Near Sihanoukville
Koh Ta Kiev is close enough to Sihanoukville to be a practical half-day trip but far enough from the port to have cleaner water than the immediately adjacent mainland dive sites. The island has some resort development but has maintained more natural character than Koh Rong. The dive sites on the outer edges of the island have hard coral in decent health and a full range of the smaller reef species characteristic of the Gulf of Thailand. Flatfish and nudibranchs are reliably found on the sandy rubble sections. Open Water appropriate throughout.
9. M'pai Bay (Koh Rong North), Night Dive
The shallow bay at the northern tip of Koh Rong is known locally for two things: bioluminescence in the warm months, when the plankton-laden water glows blue-green when disturbed, and productive night dives. The bioluminescence makes a night swim or shallow dive here genuinely memorable — disturbing the water with a hand produces a streak of cold blue light. Beyond the bioluminescence, the bay's sandy and rubble bottom after dark produces octopus hunts, hermit crabs, and the occasional flamboyant cuttlefish. Depths in the bay rarely exceed 10 metres. All certification levels appropriate.
10. Ream National Park Waters, Near Sihanoukville
The marine section of Ream National Park, just east of Sihanoukville, encompasses mangrove estuaries and shallow reef systems that are officially protected though enforcement has historically been inconsistent. The inshore reefs have suffered human impact but parts of the outer park boundary retain reasonable coral health. Dugong have been reported in the seagrass beds within the park — one of the few places in Cambodia where this is realistic — though sightings are not reliable for divers. The park's ecological importance makes it worth visiting for conservation-minded divers even if the diving itself is not exceptional.
Planning a Diving Trip to Cambodia
The best diving season runs from October through May, with November through April offering the most settled sea conditions and best visibility. June through September is the rainy season, and the Gulf of Thailand can become rough and murky. Most operators are based in Sihanoukville, though the rapid development of that city has pushed some quality operators to base themselves on the islands. Koh Rong has a growing dive scene with accommodation ranging from budget bungalows to small resorts. Equipment hire is available in Sihanoukville and on the main islands but is variable in quality; serious divers should bring their own regulators and computer. Open the map to explore Cambodian islands and dive sites across the Gulf of Thailand.