Roatán is a strip of green hills forty kilometres long in the Caribbean, the largest of the Bay Islands of Honduras, and it lies on the second-longest barrier reef on Earth. The Mesoamerican reef runs a thousand kilometres from Mexico down to here, and it wraps this island almost the whole way round. From a small plane or a hilltop it reads as a pale line of surf drawn along the coast, bright shallows inside it and deep indigo outside. At West Bay you wade off powdery white sand, and within a few strokes you are over the reef itself. Sergeant majors swarm the coral heads, parrotfish crowd the same rock, and turtles and rays cross the sand between them. On the north shore the seabed shelves gently and then stops. The reef edge falls away into a vertical wall, and divers sink along it past barrel sponges and black coral, with eagle rays cruising the drop-off and groupers hanging in the shadows.
Boats run out to the cayes and mangrove channels scattered off the shores, where you step onto near-empty sandbars and snorkel reef flats straight off the side. Everything else on the island arrived the same way, by sea. The main town, Coxen Hole, is named after John Coxon, an English buccaneer who raided Spanish treasure ships in the 1600s, when these deep coves sheltered crews doing the same. In 1797 the British deported thousands of Garifuna, an Afro-Indigenous people, from St Vincent and put them ashore here; only about half survived the crossing. The survivors founded Punta Gorda, the oldest Garifuna settlement in Central America, and it still keeps its own language, its drums and its Punta dance. The whale sharks everyone asks about gather off Utila, the next island west, rather than here. What Roatán has instead is Mary's Place, where old earthquakes split a coral head into canyons narrow enough to swim single file, walls of sponge and black coral at both shoulders and the crevices dropping away past thirty metres below your fins.