Koh Kood sits 85 kilometers from mainland Trat, the last inhabited island before Cambodia's maritime border, and its fringing reefs remain among the least-trampled in the Gulf of Thailand.
Annual visitor counts hover near 60,000, a fraction of Koh Samui's four million, and the island's 2,000 permanent residents cluster in five fishing villages along the western shore. No paved roads reached Koh Kood until 2018, and the first asphalt route — a nine-kilometer strip linking Ban Khlong Hin Dam to Ao Salad Pier — still leaves most of the island's 105 square kilometers reachable only by dirt track or longtail boat.
The island's shallow reef systems stretch along both coasts, but the eastern shoreline between Ao Phrao and Ao Tapao holds the densest hard-coral formations, sheltered from the southwest monsoon by Koh Kood's central ridge. Marine biologists cataloged 87 reef-building coral species here in a 2019 survey conducted by the Department of Marine and Coastal Resources, including rare stands of staghorn acrorite and massive Porites colonies exceeding four meters in diameter. Visibility ranges from six meters during August's plankton blooms to 22 meters in the January-to-March dry window, when northeasterly winds drop to five knots and surface chop disappears by mid-morning.
Private snorkeling Koh Kood operations launched in earnest after the 2016 opening of Laem Sok Ferry Terminal in Trat, which cut the mainland crossing from three hours to 90 minutes and brought the island within day-trip range for the first time. Most charters depart from Ao Salad or Ao Noi on the northwest coast, where a fleet of 40 licensed longtails operates under the Koh Kood Boatmen's Cooperative, a self-regulating body formed in 2014 to enforce reef-approach protocols and rotating mooring zones. Captains receive annual reef-ecology training from the cooperative's five-member environmental committee, and every vessel carries bilingual laminated reef-identification cards produced by the Marine Science Institute at Burapha University.
The absence of mass-market infrastructure means chartered reef access remains the primary model. No large tour operators maintain permanent bases on Koh Kood, and the island's eight dive shops together own fewer than 30 boats, forcing advance booking during the November-to-February peak. The cooperative's mandatory 50-meter reef buffer — double the national standard — keeps hull noise and anchor damage minimal, and quarterly coral-health assessments published by the Trat Provincial Fisheries Office have recorded stable or improving coverage across all monitored sites since 2020.
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