Omijima vs Echizen: Sea of Japan's Two Top Dive Sites Compared
2026-03-16
Omijima (Yamaguchi) and Echizen (Fukui) are the Sea of Japan's two premier dive sites. Their annual averages are remarkably close — Omijima 9.1m (2,095 obs) and Echizen 9.7m (2,653 obs), just 0.6m apart. Yet their seasonal patterns differ significantly. Echizen has a strong summer peak while Omijima stays stable year-round. We compared them using real dive log data.
9.1m
Omijima avg
9.7m
Echizen avg
2,095 obs
Omijima obs
2,653 obs
Echizen obs
Monthly Visibility Comparison
| Month | Omijima(m) | Echizen(m) |
|---|---|---|
| Jan | 8.5m | Closed |
| Feb | 8m | Closed |
| Mar | 7.8m | Closed |
| Apr | 8.2m | 8m |
| May | 8.5m | 8.5m |
| Jun | 8.8m | 9.2m |
| Jul | 9m | 10.2m |
| Aug | 9.1m | 10.9m |
| Sep | 10.5m | 10.5m |
| Oct | 10.2m | 10m |
| Nov | 9.8m | 9.5m |
| Dec | 9m | Closed |
Key Differences Between the Two Sites
Echizen's Summer Peak: Aug 10.9m
Echizen reaches its annual peak of 10.9m in August, beating Omijima's 9.1m by 1.8m that month. The Sea of Japan's summer visibility benefits from the Tsushima Warm Current, and Echizen receives this benefit more strongly.
Omijima's Stability: Diveable Year-Round
Omijima maintains 7-9m visibility even in winter, offering 12-month diving. While Echizen closes in winter, Omijima is a year-round Sea of Japan dive destination. Winter Omijima offers excellent macro life including nudibranchs despite cooler water.
Diving Season Length
Omijima operates 12 months, Echizen roughly 8 months (April-November). Sea of Japan winter storms and cold water make Echizen winter operations impractical. For year-round diving, Omijima has a clear advantage.
Summary: When to Choose Which
Choose Echizen When
- Summer (Jul-Sep) for best Sea of Japan diving
- Targeting 10m+ visibility
- Accessing from Kansai/Chubu area
Choose Omijima When
- Winter-spring Sea of Japan diving
- Prioritizing stable visibility
- Macro life (nudibranchs etc.)
About the Data
Analysis based on real dive log data from Omijima (2,095 obs) and Echizen (2,653 obs). Limited Echizen winter data reflects seasonal closure rather than missing data.
🌊 Check Visibility Forecasts
View AI-powered 7-day visibility forecasts for 30+ dive sites across Japan.
Open Forecast App →