www.town.onagawa.miyagi.jp · Official Town
Onagawa town visitor page
Dive Spot Guide•
Benten Island
Onagawa boat wall with currents and nudibranchs.
Takenoura Benten Island is a boat-access Sanriku wall site in Onagawa with mixed cold and warm currents, a shallow training profile, and dense macro life on sea squirt shelves.
About Benten Island
This dive area off Onagawa on the Sanriku coast features waters influenced by the meeting of the Oyashio and Kuroshio currents, bringing both cold and warm conditions to the site. The seascape includes fixed fishing nets and aquaculture structures such as oyster and sea-squirt shelves. A highlight is a distinctive wall of ascidians. The site is known for sightings of danglerfish year-round, with spawning observed, and for its variety of northern nudibranchs.
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Where Is Benten Island?
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Community sourced coordinates.
Benten Island Planning Details
Depth range, seasonality, and planning context.
Reported Depth
2m - 12m
Depth Note
A shallow sandy bottom and wall structure make the site beginner-friendly, with the operator page listing about 12m maximum depth.
Best Season
Year-round, with different cold- and warm-water species across the seasons.
Typical Conditions
Boat-access wall diving with mixed currents, shallow training depth, and year-round macro life.
Safety & Access At Benten Island
Hazards, restrictions, and access requirements.
Key Hazards
Cold waterStrong current
Safety Notes
Mixed cold and warm currents can shift conditions quickly, so plan conservatively and keep an eye on water temperature.
Access Restrictions
Use the Onagawa dive center or port-based boat access and follow local operator guidance.
Legal Notes
Onagawa sits in a Sanriku coastal tourism setting; follow park and port rules.
Local Intel For Benten Island
Community notes to help plan your visit.
Scuba Diving
Scuba diving includes exploring ascidian walls and diving near fixed nets and aquaculture shelves.
Freediving
The shallow profile and wall structure can work for controlled freedive sessions, but it is best treated as a guided boat wall.
Snorkeling
Snorkeling is not the main use case here; current mixing makes this a better scuba wall than a casual snorkel stop.
Wildlife at Benten Island
Species commonly reported at this site, with direct links into their wildlife guides.
Recent Logged Visits At Benten Island
Community dive logs and visit reports for this site.
Dive Spot Log Averages At Benten Island
Average conditions based on logged dives & visits.
No community dive data has been logged here yet. Be the first to record a dive and seed the averages.
