Kashiwajima Island — Diving & Snorkeling Paradise

Kashiwajima is a small island off the coast of Tosashimizu, surrounded by some of the clearest water in Japan. The island sits in the path of the warm Kuroshio Current, which brings tropical fish, coral, and exceptional underwater visibility (often 20+ meters). Diving and snorkeling here reveal a world of butterflyfish, wrasse, sea turtles, moray eels, and seasonal schools of barracuda. The water temperature remains above 20°C even in winter, making it a year-round dive destination.

The island itself is tiny — you can walk around it in 30 minutes. There are no hotels, just a few guesthouses, dive shops, and a small fishing port. The vibe is quiet, unhurried, and focused entirely on the ocean. Most visitors come for the day, diving or snorkeling in the morning and returning to the mainland by evening.