Koh Kham Underwater Park

Koh Kham is a small island off Sattahip, within day-trip range of Pattaya, that the Royal Thai Navy manages directly, and that management shows up in how you visit it: the navy runs the ferry, sets the fees and fixes the boat times. As of November 2026 the navy opens the island every day of the year, so the thing to check before you go is the boat timetable and the weather.

When it’s running, the appeal is straightforward: a short ferry crossing from Samaesan pier lands you on a compact island with a shallow coral fringe close to shore. Snorkeling is the main activity, with visibility good enough on calm days to make out reef fish without diving gear, and a glass-bottom boat option covers anyone who’d rather stay dry. A wooden boardwalk runs along part of the beach, useful for reaching quieter stretches without cutting across the coral itself.

Watch out: Old travel blogs and tour listings still describe the island as often closed. Check the navy’s own timetable on kohkham.com or call 0 3312 4848 (weekday office hours), rather than relying on a review from a year or more back. The navy can cancel boats in rough weather without notice.

Insider Tip: Morning ferries reach the island before onshore winds pick up, which matters more here than at most snorkel spots since the reef is shallow and gets stirred up once the water isn’t flat.

The navy’s tight control of access is part of a broader conservation effort on this stretch of coast, alongside the coral restoration and marine education work based at nearby Samaesan. It’s the reason the reef here has held up better than many similarly accessible mainland-adjacent snorkel spots, even with steady day-trip traffic.

Pair a visit with nearby Koh Samae San or the Thai Island and Sea Natural History Museum on Samaesan Island, both departing from the same stretch of coast.