Rangiroa

Everything is boat diving and everything is set by the tide. Runs out to the passes take minutes, but the timetable follows the tide table rather than the clock, so departure times shift a little each day and a normal day is two dives at fixed tidal windows. Briefings spend as much effort on where to sit in the water column and when to let go as on what might swim past, and groups stay tight because the pass sets the pace, not the guide.

Only two navigable passes cut the atoll rim, and they behave differently. Tiputa is the narrower and deeper of the two, with a plateau on the ocean side where divers wait in open water for the flood to pick them up. Avatoru moves less water and takes the overflow when Tiputa is running harder than a group can handle. Away from the passes the outer reef falls off in walls, and the shallow lagoon side is the ground trips fall back on when the tide is out of phase or swell shuts the channels down.

The set piece is the incoming drift, and it is closer to being carried than to swimming. You drop outside, hang in the blue while the pass draws breath, then get drawn in with everything else using the current that hour. It ends abruptly in flat lagoon water, and the stop at the inside end is often the busiest part of the dive rather than the quietest, since that is where the resident dolphins tend to decide whether to come and look at you.

Rangiroa rewards divers who are comfortable being passengers. Buoyancy control in moving water counts for more than a long logbook, and anyone tense in current will spend the dive fighting it instead of watching it. The diving concentrates on a handful of sites rather than spreading thin, so the atoll works well as one leg of a trip alongside Tahiti or a second atoll; the lagoon is large enough that a run to its far side is a full day out on its own.