High Risk of Poor Visibility: Sites Where Sub-8m Days Hit 40%+
2026-03-16
Knowing the 15m+ probability is nice, but knowing the sub-8m probability may be more important. Below 8m, you can barely see beyond your buddy — wide-angle photos are impossible, and stress increases. Understanding risk helps you choose wisely.
Sub-8m Risk Ranking
Deep inside West Izu harbor. Summer 5–6m is normal
Enclosed bay + sand floor. Macro paradise but low clarity
Sea of Japan. Winter is the worst
Beginner training hub. Inner bay = lower visibility
Sea of Japan. Winter is near-shutdown levels
Sea of Japan, Yamaguchi. Autumn–winter decline
Hokkaido. Spring crash to 4.3m
Eastern Kochi. River runoff impact
Eastern Kochi. Only 4.4% chance of 15m+
Popular for caves but July dips to 8.4m
Why Low-Vis Sites Are Still Worth Visiting
Osezaki Bay (54.6%): Macro Mecca
Over half the days are sub-8m, but its sand-dwelling biodiversity is Japan's finest. For macro subjects (ornate ghost pipefish, gobies, frogfish), 5m visibility is plenty. The ultimate 'choose by creatures, not clarity' site.
Hirasawa (39.3%): Beginner-Friendly Waters
Lower visibility but calm bay with easy beach entry — perfect for beginner training and skill practice. Low-vis days are actually ideal for navigation training.
Tips to Reduce Risk
- Choose season: Sea of Japan in summer, Pacific in winter reduces risk
- Check weather: wind direction can shift visibility 2–3m
- Bring a macro lens: enjoy low-vis days with close-up photography
- Check shop's latest report: same-day info is most accurate
About the Data
46,000+ observations from sites with 100+ data points. Sub-8m threshold based on (min+max)/2.
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