The Kerama Islands are considered one of the best diving destinations in Japan. The water clarity is exceptional — 30 to 50 metres visibility is common — and the coral reefs around Tokashiki are diverse and in good health. Dive sites include walls, gentle slopes with hard coral gardens, and a handful of deeper sites with large sea fans and pelagic fish.
Several dive shops operate out of Aharen village offering two-dive day trips, PADI courses for beginners, and equipment rental. The shops fill up quickly in summer (July–August); book ahead. Spring and autumn offer uncrowded diving with water temperatures that are comfortable in a 3mm wetsuit.