Hawaii

First Cathedral off Lanai island is a dramatic lava tube and cavern system whose domed main chamber is pierced by shafts of light filtering through holes in the rock ceiling, creating a cathedral-like atmosphere at 16 m. Spinner dolphins rest in the calm water near the entrance, and the surrounding reef hosts monk seals, eagle rays, and the endemic Hawaiian cleaner wrasse. The site was extensively surveyed by Dr. Sylvia Earle and remains one of Hawaii's most celebrated dives.

The Garden Eel Cove night manta dive off Kailua-Kona is one of the most magical dives in the world — divers kneel in the shallow sandy bowl at 12 m shining lights upward to attract zooplankton, and resident reef mantas perform loop after loop over the divers' heads in the plankton-rich water. Up to 20 mantas have been counted in a single dive, and because these individuals are photographically identified and non-migratory, encounters are nearly guaranteed most nights of the year.

Molokini is a partially submerged volcanic crater 4 km off Maui's south coast that forms a natural protected amphitheatre with flat-calm water and visibility regularly exceeding 30 m. The inner crater slopes from 5 to 25 m and is home to white-tip reef sharks, eagle rays, and a remarkable density of Hawaiian reef fish including endemic species found nowhere else on Earth. The outer back wall drops 100 m and is reserved for experienced divers.

Aloha Deep Hawaii Divers is based in Kailua-Kona on the Big Island, renowned globally for the extraordinary manta ray night dive at Garden Eel Cove — where a dozen or more manta rays perform graceful barrel rolls through diver torch beams just metres from the sandy bottom. Hawaiian diving uniquely blends tropical Indo-Pacific species with temperate endemics found nowhere else on Earth, including the Hawaiian cleaner wrasse, Potter's angelfish, and the state fish — the humuhumunukunukuapua'a. Their boat dives also cover lava tube arches, spinner dolphin encounters, and the rare pelagic mola mola.

Maui Reef Research Divers operates from Lahaina, combining commercial dive charters with active coral reef monitoring under a partnership with the Hawaii Institute of Marine Biology. Maui's dive sites span volcanic lava arches, black sand desert plains, and colourful coral gardens fed by upwelling currents between Maui and Molokini crater — one of America's most visited marine sanctuaries. Their citizen-science Reef Check dives allow certified guests to contribute to official state reef health databases while exploring sites few tourist operators visit.