Sail Rock.

Sail Rock is not a reef or an island. It is a single granite column whose top breaks the surface by a few meters and whose base rests at around forty. Around it, the water moves slowly. Barracuda hold in long, loose circles at twenty. Batfish gather near the top. In February and March, and again in September and October, whale sharks pass through without hurry. We leave Bophut at first light and reach the rock before the charter fleet from Koh Tao and Koh Phangan, which gives us the pinnacle to ourselves for the morning's best light. The day is not fixed. Minseo reads what the water is doing and shapes the dives around it — long surface intervals, lunch aboard, the pinnacle at depth when conditions invite depth, the reef line when they don't.