The sea floor between Martinique and Dominica drops to more than 1,000 metres within sight of land. That trench is the reason spinner and bottlenose dolphins hunt so close to the island's leeward shore, and it is the geological accident on which the modern fleet of martinique boat tours quietly depends. Martinique's maritime culture predates leisure sailing by centuries. The gommier — a hull carved from a single gum tree, rigged with a triangular sail — was adapted by Kalinago builders and later by Creole fishermen along the Atlantic coast. Its descendant, the yole ronde, has no keel and no deck; crews balance it with long wooden poles slung over the windward side. UNESCO inscribed the yole and its regatta tradition on the Representative List of Intangible Cultural Heritage in 2020. Many skippers running an excursion en bateau Martinique today learned the water in those boats. The island's coastline divides into three distinct sailing grounds. The south-west, anchored by Marina du Marin — the largest marina in the Lesser Antilles — opens onto the Baie de Fort-de-France and the calm channel toward Trois-Îlets. The Atlantic east, around Le François, is protected by a barrier reef enclosing the Fonds Blancs: shallow sandbanks of white marl where the water stands waist-deep a kilometre offshore. Josephine's Bath takes its name from the Empress, born at Trois-Îlets in 1763, though the legend that she bathed there is nineteenth-century embellishment rather than record. Nearby Chancel Islet holds the ruins of an eighteenth-century sugar estate and a free-ranging population of iguana delicatissima, a species now extinct across most of its former range. Between those two coasts lies the mangrove of the Baie de Genipa, the largest in the Lesser Antilles. Four species of mangrove grow there in bands — red, black, white and buttonwood — filtering sediment before it reaches the reef and sheltering juvenile fish, herons and land crabs in channels narrow enough that a small boat must cut its engine. Hawksbill and green turtles graze the seagrass beds off Anse Dufour and Anse Noire, protected under French law since 1991. What a Martinique catamaran tour offers, then, is not a single monument but a rotating cross-section of the island: volcanic cliffs below Mont Pelée, drowned sandbanks, colonial ruin, and reef. Any well-run martinique boat tours tour is finally a lesson in how narrow and how varied this 1,128-square-kilometre island really is.