Koh Tang

Sihanoukville · Sihanoukville Province · Cambodia

Koh Tang is one of those dive destinations where the journey is part of the story. Lying roughly sixty kilometres southwest of Sihanoukville in the open Gulf of Thailand, this jungle-covered island serves as a Cambodian military outpost and is off the beaten path by any definition. The four-to-five-hour boat ride filters out casual visitors, leaving the reefs to dedicated divers willing to make the trip. What they find is some of the healthiest and least-dived reef in the Gulf of Thailand. The island's military status has inadvertently created a marine sanctuary. Fishing is restricted, and the absence of tourist development has left reefs in a condition that Gulf veterans describe as what Koh Tao looked like thirty years ago. Hard coral coverage is excellent, with massive porites colonies, table corals, and branching acropora thriving on the granite boulders that characterise the underwater terrain. Fish density matches the coral health — schooling barracuda, giant trevally hunting in packs, and enormous groupers grown to sizes rarely seen on more accessible reefs. Blacktip and whitetip reef sharks are regular sightings at twenty to thirty metres, moving with the confidence of predators that have not learned to fear humans. Moray eels coil in boulder crevices, lobsters wave antennae from under overhangs, and batfish schools hang in the water column like silver shields. For macro enthusiasts, the boulders harbour nudibranchs, flatworms, and shrimp species that benefit from minimal diver disturbance. Koh Tang carries historical weight beyond its marine life. In May 1975, US Marines fought the last battle of the Vietnam War era here during the Mayaguez incident. The island's jungles still hold relics from that engagement. Diving here carries an awareness of layers — natural beauty growing over human conflict in a place where the sea has had the final word. Trips should be arranged through established Sihanoukville operators who maintain necessary military permissions.