Koh Kruai-Ko Kham-Ko Plai tin

Ko Kruai, Ko Kham, and Ko Plai Tin are three small islands inside Khao Laem Ya-Mu Ko Samet National Park, a short boat ride off Mae Phim Beach in Rayong. At low tide, exposed sand bars link the islands closely enough to wade between them — the kind of tidal land-bridge Thai boat operators call a “split sea.” A national park fee applies here (roughly 300 THB for foreign adults, 40 THB for Thai nationals, though rates are periodically revised — check with your boat operator before booking).

Ko Kham carries the most usable beach of the three, a sandy stretch backed by scrub where day-trippers set up for a few hours between snorkelling sessions; its far side turns rocky, with clearer water over a stony bottom. Ko Kruai and Ko Plai Tin are smaller and less developed — mostly rock outcrops and tide pools rather than sunbathing sand — and see fewer visitors as a result. Shallow reef sits close to shore around Ko Kham and Ko Kruai, with enough coral cover and reef fish to make snorkelling worthwhile without a long swim out.

Insider Tip: Ask your boat driver for the tide schedule before you go — the sand bar between the islands is submerged for hours each day, and turning up at the wrong time means a swim rather than a walk between islands.

None of the three islands has accommodation, so this is strictly a day trip: boats run from piers near Mae Phim Beach and Ban Phe, about 20 minutes each way, and most operators sell it as a multi-island itinerary rather than a dedicated trip to just these three. Combining it with a call at Ko Talu or Ko Kudi — both in the same park cluster — is the common pattern and better value than chartering separately.

Watch out: There’s no shade or facilities on any of the three islands. Bring water, sun cream, and reef-safe sunscreen given the snorkelling, and expect to pay the park fee in cash at the pier or on the boat.

More of Rayong’s outer islands sit in the same national park cluster: Ko Talu, Koh Kudi (Ko Kut), and Koh Khangkhao.