Sipadan

Nobody sleeps on Sipadan. The resorts were cleared off the island in the mid-2000s and it now holds a jetty, a ranger station and a security post, so everyone dives it as a day trip from Mabul, Kapalai or Semporna. That shapes the whole week: boats leave early, each operator works to a fixed daily allocation of permits, and most divers get one or two island days out of a longer trip. Three dives, surface intervals on the beach or aboard, then the run back, with the remaining days spent on the reef and muck sites closer to the mainland.

Everything at Sipadan happens at an edge. The reef flat around the island ends abruptly and the wall goes, so there is no slope to ease down and depth becomes a decision rather than something the topography hands you, which puts more weight on buoyancy and gas planning than a sloping reef would. Sites differ mainly by what the water is doing. Corners and points accelerate the current and concentrate schooling fish, while the sheltered stretches are slow swims past sea fans and coral heads with turtles resting under overhangs.

The set pieces are what people book for. On the exposed corners you tuck in against the wall while barracuda wheel overhead in a slow column and jacks pack in tight below them, with sharks working the outside of it. The cavern in the drop-off is a different kind of dive and a sober one; the skeletal remains inside are usually explained as animals that swam in and could not find the way out, though that account is repeated far more often than it is tested. Most divers look in from the mouth, and anything past the entrance is guided and restricted rather than casual.

It rewards divers who are comfortable being moved around. Nothing here is technical, but moving water is normal and ease in it decides whether you watch a school or chase it. Turtles are so constant that people stop pointing them out by the second dive, which makes the island oddly restful between the set-piece corners. Diving runs all year, and March to September is the strongest run of months, which is also when island days need arranging furthest ahead.