Koh Ngam combines shallow coral reefs, rocky pinnacles, walls, caves and a wreck across a compact island group off Chumphon. The vast majority of sites suit beginners, with a handful of deeper reef dives for intermediate divers. Boat access dominates, though a shore entry is available at House Reef. Signature encounters include the Bluespotted Fantail Ray and Whale Shark, alongside resident Pink Skunk Clownfish, Porcupinefish and Grunt. The HTMS Prab 741 adds an artificial reef dimension rarely found at similar-scale sites.
Monthly water temperature across Koh Ngam's sites, from satellite sea-surface data corrected for depth. The band shows the site-to-site spread.
Water stays warm throughout the year, peaking in the warmer months of April and May and easing slightly into the cooler end of the range in January, February and December. Visibility can vary considerably depending on season and site, with calmer periods from March through to May drawing the strongest diver interest. November and December see the fewest favourable conditions, suggesting a seasonal low worth avoiding for the clearest water.
11 operators
5 more sites to explore
Water temperature around Koh Ngam ranges from about 28°C in January to 31°C in April, based on satellite sea-temperature data for its dive sites.
With water around 28–31°C, a rash guard or 3mm shorty works in Koh Ngam year-round.
Fin maps 17 sites in Koh Ngam (16 scuba diving sites and 8 snorkelling spots, with some suited to both).
Koh Ngam is one of the few areas in the Chumphon region where Whale Shark sightings are regularly recorded across a good proportion of sites. Bluespotted Fantail Ray is seen very commonly, and Barracuda, Batfish and Groupers are also frequently observed. Scorpionfish are present at many sites, so watching where you place your hands on reef structures is always wise.
The large majority of sites in Koh Ngam are rated beginner level, including popular spots such as Koh Khai, Hin Chedi, House Reef and Ao Kruad. A smaller number of sites, including Sam Laem and Koh Ran, reach greater depths and are better suited to intermediate divers. This mix makes Koh Ngam a practical destination for mixed-ability groups.
Almost all sites in Koh Ngam require a boat to reach, which is typical for an offshore island group. The one exception is House Reef, a shallow beginner-friendly site that can be entered directly from shore. Ao Mook also lists both shore and boat entry options, giving divers a little flexibility without a full boat commitment.
Koh Ngam covers a wide variety of site types for a compact area. Coral reefs are the backbone, but the group also includes pinnacles at Hin Chedi and Hin Look Bat, a wall and cave at Hin Look Bat, swim-throughs at Koh Ngam Noi, and the wreck of the HTMS Prab 741 serving as an artificial reef. Koh Jorakea adds further artificial reef structure alongside natural coral.
