Long Caye

You drop onto the coral gardens on top of the wall, which average about 10 metres on the west coast of the caye and 15 metres on the east. Massive purple, pink and beige sea plumes stand tall over giant sea rods, brain corals and boulder star corals, with branching vase sponges, barrel sponges and yellow tube sponges filling the gaps. This is trumpetfish country, and horse-eye jacks, great barracuda, Creole wrasse, Spanish hogfish and midnight parrotfish work the same ground.

From the gardens you move out to the lip, where the ground gives out and the wall drops to the sea floor several hundred metres below. The face is hung with sea fans, stove-pipe sponges, sea whips and bushy black corals; squirrelfish tuck into the cuts and pike blennies sit cocked on the fan branches. Caribbean reef sharks and blacktips patrol out here, black groupers rise from the depths for a look, and oceanic triggerfish hang in the blue nearby.

Individual sites along the caye have their own character: Silver Caves is named for the dense schools of silversides that shelter in its channels, where horse-eye jacks come in to hunt. Dos Cocos is a night dive, with large tarpon hunting aggressively in the dark and using divers' torch beams to pick off reef fish, plus slipper and spiny lobsters, hermit crabs and reef squid drawn in by the lights. The atoll holds UNESCO World Heritage status and three national protected areas, but still takes human impact from uncontrolled fishing and tourism.