Fakarava

The atoll works as two dive bases at opposite ends of a very long lagoon. Most visitors stay in the northern village, Rotoava, and reach the pass there in minutes; the southern channel sits at the far end, reached either by a long lagoon crossing for the day or by moving down to the few small pensions at Tetamanu beside it. Liveaboards solve the geography differently, working both ends on one trip and adding neighbouring Tuamotu atolls in between.

Tides set the schedule. On the flood, ocean water pushes in and the channel runs clean; on the ebb the lagoon empties out and takes the clarity with it, so trips are built around the incoming window, and a single day can hold two or three passes through the same water at different strengths. Guides read the strength off the surface before anyone gears up, and a window missed by half an hour changes the dive completely.

The two passes dive nothing alike. Tumakohua in the south is narrow enough that divers tuck into the coral out of the flow and watch the sharks hold position in front of them, so most of the dive is spent stationary. Garuae in the north is wide enough to feel like open water rather than a corridor: more ground covered, animals met out in the blue, a longer swim to anything. Around the full moon in June or July the south adds night dives, when the sharks hunt in the dark.

This is a single-purpose destination and honest about it. There are few sites, and the same pass is dived over and over at different tide states, so the appeal is depth of experience rather than variety; divers who want a new site every tank will get restless. Comfort in strong water and the discipline to stay off the coral matter more than a long logbook. Facilities are thin, especially at the southern end, where power, water and meals all come from the pension you are staying in.