Koh Thalu (Bang Saphan)

Koh Thalu, Koh Sang, and Koh Sing sit together off Bang Saphan Noi in Prachuap Khiri Khan, but they’re not three equal destinations — Koh Thalu is the one with a resort and a name of its own; Koh Sang and Koh Sing are smaller, undeveloped islets that come along as snorkel stops on the same boat trip. There’s no national park fee on any of the three, so the only real cost is the boat transfer or a night at the resort.

Koh Thalu takes its name from a rock formation pierced clean through by the sea — a small natural arch on the island’s shoreline that boats pass on the way in. Koh Talu Island Resort, running here since the late 1970s, has the only accommodation, restaurant, and dive centre in the group, plus a shoreline turtle-conservation program that cares for hatchlings before release. Guests and day visitors both snorkel the reef fringing the resort beach, where shallow coral holds parrotfish and reef fish close enough to see from the surface without diving down. Koh Sang and Koh Sing, a short boat hop further out, are smaller and undeveloped — no restaurant, no jetty infrastructure, just rock and a narrow strip of sand — and most people see them only as an add-on stop on a longer snorkel circuit rather than a destination in themselves.

November to April brings the calmest crossing and clearest water; the rest of the year the boat ride from Bang Saphan gets choppier and some operators cut trips to Koh Sang and Koh Sing first, since Koh Thalu’s resort keeps its own transfer running for guests regardless.

Insider Tip: Book a night at Koh Talu Island Resort rather than a day trip if you want to see all three islands properly — most day-boat itineraries only stop at Koh Thalu itself, with Koh Sang and Koh Sing added only when the sea’s calm enough for the extra crossing.

Watch out: Koh Sang and Koh Sing have no facilities at all — no shade shelter, no drinking water, no toilet. If your boat adds them to the itinerary, treat it as a brief swim stop, not a place to spend the afternoon.

Base yourself in Bang Saphan for the shortest crossing — Hat Ban Krut and Hat Thang Sai are the nearest mainland beaches with hotels if you’d rather day-trip than stay on the island.