Triton Bay

Everything runs off the boat. Itineraries hop between anchorages, tenders drop divers on sites a few minutes away, and the rhythm settles into three or four dives a day with night dives on the schedule. There is no shop to fall back on and little scope for changing plans: if the wind turns, the boat moves and the day moves with it. Charters cluster into a window running roughly October to March, strongest in November and December, and the bay goes quiet for the middle of the year.

The land is karst and it carries on underwater. The limestone cliffs and undercut islets around Aiduma and Namatote continue below the surface as walls, ridges and isolated bommies. Water in the sheltered inner bays is green and heavy with particles, while the exposed pinnacles catch enough current to feel like a different destination, with schooling fish and real drift. The two sit close enough together that both can happen in a single morning.

Low visibility shapes how the place is dived. Soft coral colour goes grey in ambient light at depth, so you swim past what looks like scrub until a torch or a strobe lands on it and the face turns orange and red. Photographers work close and wide for that reason, and most divers cover far less ground per dive than they would somewhere clearer. It is a destination for people who read visibility as a lighting problem rather than a defect.

The other set piece is arranged rather than stumbled on. Crews negotiate access with the fishermen working the bagan lift-net platforms, and divers get in beside the nets early, once the night's fishing is done. Beyond that, the appeal is texture and remoteness. It makes a poor first liveaboard, since the bay is a long way from medical help and the diving is dark and current-swept, but it rewards anyone who has already worked through Indonesia's better-known reefs.