Molokini is a small crescent-shaped islet about 5 kilometres off the south Maui coast — the exposed rim of a partially submerged volcanic crater. Inside the crescent, the visibility can exceed 30 metres and the water is packed with fish, coral, and — on good days — eagle rays, white-tipped reef sharks, and spinner dolphins.
Molokini is accessible only by boat. Tour operators depart from Ma'alaea Harbor and Kihei Boat Ramp; trips typically run from early morning to midday to beat the afternoon winds. Four Winds II, Trilogy, and Ali'i Nui run reputable snorkel cruises. The back wall of the crater, accessible on dive-only trips, is a sheer drop to over 90 metres and one of Maui's most dramatic dive sites.
Go early: by 10am the crater is crowded with tour boats, and the calm morning water makes for easier snorkelling than the choppier afternoon conditions.