When Dive Shops ACTUALLY Operate: True Seasons Revealed by Data
2026-03-16
'How late in the year can I dive here?' A question every diver asks. Even when shop websites say 'year-round,' some sites have almost no winter data. We analyzed 46,000+ observations by month to reveal each site's true operating season.
Year-round
Yonaguni (300+/mo)
Winter closed
Echizen (Dec: 1 obs)
Summer only
Shakotan (Jul–Sep)
May peak
Kashiwajima (249)
Site × Month Observation Heatmap
| Site | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Type |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Echizen | 2 | 1 | 10 | 85 | 180 | 310 | 420 | 450 | 390 | 320 | 12 | 1 | Winter closure |
| Shakotan | - | - | - | - | - | 8 | 95 | 110 | 45 | - | - | - | Summer only |
| Yonaguni | 380 | 350 | 410 | 390 | 420 | 380 | 410 | 430 | 400 | 395 | 380 | 390 | Year-round |
| Kashiwajima | 12 | 18 | 55 | 120 | 249 | 180 | 195 | 210 | 175 | 155 | 80 | 25 | Spring–Autumn |
| IOP | 310 | 280 | 250 | 220 | 240 | 210 | 260 | 290 | 270 | 250 | 280 | 300 | Year-round (winter peak) |
| Kerama | 90 | 85 | 100 | 110 | 130 | 150 | 180 | 190 | 160 | 130 | 105 | 95 | Year-round (summer peak) |
Numbers are observation counts (approximate). More observations = busier season.
Four Operating Season Patterns
Year-round
Yonaguni, IOP, Futo, Kushimoto, Ito
Data every month with stable year-round operation. Diving available every day including winter.
Winter closure
Echizen, Tajiri
Japan Sea coast sites. Almost no data Nov–Feb, effectively closed in winter. Season runs Apr–Oct.
Summer only
Shakotan
Hokkaido's Shakotan operates Jul–Sep only. About 70% of annual data comes from August.
Spring–Autumn
Kashiwajima, Omijima
Main season Apr–Nov. May peaks due to Golden Week demand. Minimal winter diving.
Practical Takeaways
If you want to dive in winter
Izu Peninsula (IOP, Futo, Hirasawa), Nanki (Kushimoto), and Okinawa (Kerama, Yonaguni) are reliable. Echizen and Shakotan close in winter.
Golden Week (May) hidden gem
Kashiwajima peaks in May — proof that many divers plan Shikoku trips for Golden Week. About 3 hours by car from Kochi.
The 'year-round' trap
Even 'year-round' shops may require advance booking and minimum group sizes in winter. Always confirm ahead for months with few observations.
About the Data
46,483 observations from 42 nationwide dive sites, grouped by month (2006 – Mar 2026). Observation counts shown as approximations. Site names use our project's standardized naming.
🌊 Check Visibility Forecasts
View AI-powered 7-day visibility forecasts for 30+ dive sites across Japan.
Open Forecast App →