Pulau Ai

Ai is a speck of nutmeg-growing land ringed by reef that would headline most countries. Its shelf of intact hard coral tips over into walls cut with chimneys and overhangs, and the crossing-season water here can be so clear the wall seems lit from within. Turtles are constant, sweetlips and snapper crowd the coral heads, garden eels pattern the sandy shelf, and the corners deliver periodic drama, jacks, barracuda, an eagle ray, occasionally something larger from the open Banda blue. Villages on the island still farm the spice that once made this speck internationally contested. As the gentle counterweight to the crossing's exposed seamounts, Ai is where liveaboard logbooks catch their breath.

The moment you come for: Glass-clear wall diving; intact hard-coral shelf; easy profiles between the crossing's big-water sites.

Topography: Fringing hard-coral shelf breaking into walls and buttresses around the small island of Ai.

Current: Generally relaxed drifts along the island's walls, firming up at the exposed corners.

Hazards: Little in settled weather beyond standard wall depth discipline.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).