Mu Ko Ngam (Koh Ngam Islands)

Mu Ko Ngam is a small island group off Chumphon in the Gulf of Thailand, inside Mu Ko Chumphon National Park, which means the park’s entrance fee applies here, not free access. Foreign adults pay 200 THB (100 THB for children), Thai adults 40 THB (20 THB for children); most Chumphon dive-boat trips already include this in the tour price. The group centres on two islands, Koh Ngam Yai and Koh Ngam Noi, plus smaller rock outcrops nearby, reached by around an hour’s boat ride from the Chumphon coast near Pak Nam.

There’s no beach here: Koh Ngam Yai rises as a steep limestone cliff straight out of the water, used as a swiftlet’s-nest concession site, which is part of why it stays undeveloped. The draw is underwater: coral reef along both islands, stone formations running parallel to the shoreline, and a small submerged cave off Koh Ngam Yai that’s a regular stop on local dive itineraries. Gulf of Thailand visibility runs greener and less clear than the Andaman side, but the reef here holds up: snapper, trevally, and yellowstripe scad move in numbers around the rock piles, alongside clownfish, parrotfish, butterflyfish, and the odd turtle.

Watch out: There’s no beach or dry land to relax on at Koh Ngam Yai. This is strictly a boat-and-dive stop. If you’re expecting an island you can walk around, look elsewhere in the Chumphon island chain.

Insider Tip: Koh Ngam Noi, just south of Koh Ngam Yai, gets fewer boats than its neighbour but has similar reef coverage along its own stone ridge, worth asking your dive operator to include if the main site feels crowded.

Book through a Chumphon-based dive shop rather than trying to arrange your own boat: most run combined day trips covering Koh Ngam Yai, Koh Ngam Noi, and neighbouring islands like Koh Matra, splitting the park fee and boat cost across the group.