Dhigali Haa

You drop onto the top of the thila at around 7 metres, and the reception committee is usually big-nosed unicornfish, which come in to play in the chimneys of bubbles your exhalations send up. The summit itself is busy: innumerable anthias, basslets and dottybacks hold firm in the current over the coral, and a couple of smaller pinnacles off the western edge of the thila are worth a look before you drop over the edge.

Working down the flanks takes you into canyons and caves that run to the 30 metre base. Off the reef, legions of blue-dash fusiliers hang in the blue with jacks and trevallies hunting through them, working the bait fish that swarm in huge numbers around the quieter sections of the site. Those calmer corners also hold yellow-lined snapper, small fans and scribbled filefish, and the spiral whip corals and the anemones with their pairs of plankton-sweeping porcelain crabs are what the photographers stop for.

This is a thila inside the atoll rather than a channel wall, so the big current sweeps happen elsewhere and there is time to look closely. The sessile life is small-scale to match, with no big barrel sponges or large fans, and the search everyone should make is for the Maldivian sponge snail, Coriocella hybyae, an unremarkable-looking animal endemic to the Maldives that moves at around a centimetre a day, so it will still be there when you come back round.