Chichijima Dolphin Reef

The sheltered bays and reef systems on Chichijima's western coast form the primary habitat for resident pods of Indo-Pacific bottlenose dolphins (Tursiops aduncus) and spinner dolphins (Stenella longirostris). Unlike snorkel-only dolphin swim tours, this site combines scuba diving on the shallow reef with frequent dolphin encounters — the pods regularly investigate divers ascending the reef slope at 8 to 15 m. The reef itself hosts the wrought-iron butterflyfish (Chaetodon daedalma), endemic to the Ogasawara and southern Izu Islands, in concentrations unusual even within their limited range. Sperm whales (Physeter macrocephalus) are heard and occasionally seen in the open water column outside the reef from June through October. Humpback whales (Megaptera novaeangliae) pass through January through April during their winter calving migration.