Ryuodo

Ryuoh-do Cave on Sado Island’s Ogi Peninsula is a large sea cave nicknamed the “Blue Cave” for its clear waters and glowing blue light. Popular for diving and sea kayaking, it hosts sea slugs, seahorses, and more, offering a magical experience for beginners to intermediate divers.

Ryuoh-do Cave offers nudibranchs, seahorses, manta rays, small crustaceans, and seasonal migratory fish—perfect for close-up marine life observation.