Hatsushima is a small island in Sagami Bay, about a 25–30 minute ferry ride from Atami Port on the Izu Peninsula. Thanks to the warm Kuroshio Current, it hosts a surprising variety of tropical fish rarely seen along Japan's mainland coast. The whole shoreline is rocky with no sand beach, so snorkeling access runs entirely through the Hatsushima Snorkeling Center, which oversees three graded spots: a calm beginner area inside the fishing harbor, an intermediate point off the tip of the breakwater known for cobalt-blue chromis and sea anemone colonies, and a separate advanced site. Depths run roughly 1–5 m with 8–15 m visibility, clear enough to spot fish from the surface. As of July 2026 it's in the peak June–October season, though summer jellyfish are a recurring nuisance to watch for.
A calm, sheltered beginner point inside the fishing harbor
An intermediate point off the breakwater tip with cobalt chromis and anemone colonies
Kuroshio Current brings unusually diverse — and occasionally rare — tropical fish
Hatsushima Snorkeling Center provides full gear rental, showers, and changing rooms
An easy day trip: about 25–30 min by ferry from Atami Port
Good to know
SafetyIntermediate and advanced points sit near the outer breakwater where currents can pull swimmers seaward — always use a buoy or float and never snorkel alone. Beginners should stay strictly within the harbor's designated area.
SafetyThe harbor is shared with ferries and fishing boats, so stay within the marked zone and follow the snorkeling center's guidance on boat traffic.
SafetyJellyfish stings are fairly common in summer; wear a rash guard or wetsuit to reduce exposed skin, and report any sting to staff right away.
RulesThere's no public beach anywhere on the island — you can't just walk into the water. Gear rental and check-in through the Hatsushima Snorkeling Center is required before entering.
SeasonSeason runs June–October; July water temperature is around 23–26°C. Late summer (Aug–Sep) has the richest fish life, but jellyfish numbers also rise then.
MannersDon't stand on or grab rocks, seaweed, or anemones, and don't feed the fish.
Practical info
From Atami Station it's about a 25-minute walk (or a short taxi ride) to Atami Port, then roughly a 25–30 minute ferry crossing to Hatsushima, where you rent gear and check in at the Snorkeling Center before entering the water. Ferries can be cancelled in rough weather, so confirm the current timetable and the center's operating hours before you go.
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