Ang Thong Marine Park.

Ang Thong is a marine park, which means the water is quieter here than anywhere else in the Gulf. No commercial fishing, no heavy traffic after mid-morning, no development on any of the forty-two islands. Limestone walls rise a hundred meters vertical from a sea the color of new green glass. The lagoon at the heart of the park — Thale Nai — opens at mid-tide and closes at dusk. The day is shaped for beauty more than depth. We swim, hold breath along the walls, anchor for lunch in the channel between Ko Wua Talap and Ko Phi, and spend the afternoon where the light is still good.