Elba's 147 kilometers of coastline remained inaccessible by road until the 1960s, when the island's fishing cooperatives began converting wooden tonnara vessels into passenger craft. The granite headlands that sheltered Napoleon during his 1814 exile now anchor a network of marine routes linking thirty-two named coves, seven sea caves, and two offshore wrecks visible from the surface. Elba sits at the geological hinge where the African and Eurasian plates compressed Tuscan seabeds into schist and serpentine, leaving the island's western shores dark and volcanic, its eastern beaches white quartz sand. Most Elba Island boat tour departures leave from Porto di Marina di Campo, the island's widest natural harbor, and follow one of three routes: the complete island circuit, the southern Blue Grotto corridor, or the southeastern passage to the Gemini Islands. The complete circuit is an eight-hour clockwise journey past Pomonte's 1972 Elviscot cargo wreck, the iron-rich cliffs of Punta Nera, and the lighthouse at Capo Vita, where currents meet and create standing waves even in calm weather. The southern route prioritizes swimming time, with stops at Cavoli, Fetovaia, and the Blue Grotto at Punta della Troia, a limestone chamber accessible only at low tide. The southeastern route threads between Elba and the uninhabited Gemini Islands, where monk seals were last sighted in 1974 and cormorants nest in April and May. Operators follow the Parco Nazionale Arcipelago Toscano's 2019 anchoring rules: no more than twelve vessels per cove, no anchors in posidonia meadows, and departure by 18:45 to avoid disturbing nocturnal marine life. The Blue Grotto's interior width is fourteen meters; boats enter single-file, engines off, and drift through on tidal pull. The Pomonte wreck lies in twelve meters of water, its hull colonized by sponges and damselfish. Visibility averages twenty meters from May through September, dropping to eight in winter when the Libeccio wind stirs sediment from the seabed. Most tours include snorkeling equipment, but wetsuits are recommended before June and after September when surface temperatures fall below eighteen degrees Celsius.