Data-Driven Dive Planning: 3 Steps to Choose Tomorrow's Site
2026-03-16
"Where should I dive tomorrow?" Instead of relying on intuition alone, here are 3 data-driven steps to find the clearest water. Combining seasonal trends, wind direction, and AI forecasts gives you the best chance of a great dive.
Narrow Down by Season
First, check which areas have the best visibility in the current season. Seasonal trends are very stable and serve as the most reliable first filter.
| Season | Top 1 | Top 2 | Top 3 | Why |
|---|---|---|---|---|
| Winter (Dec–Feb) | IOP | Ito | Futo | Pacific coast peaks in winter clarity. |
| Spring (Mar–May) | Okinawa (Kerama) | Koganezaki | Kashiwajima | Mainland gets spring murk. Okinawa or West Izu best. |
| Summer (Jun–Aug) | Yonaguni | Echizen | Tajiri | Islands or Sea of Japan. Pacific gets warm and murky. |
| Autumn (Sep–Nov) | Mikomoto | Kushimoto | Hachijojima | October is the annual sweet spot. Pacific coast & islands excel. |
Choose Site by Wind Direction
After narrowing by season, use the day's wind direction to pick the specific site. Wind affects both visibility and sea conditions. The basic rule: choose a site sheltered from the wind (lee side).
| Wind | Recommended | Avoid |
|---|---|---|
| NW wind | West Izu (Koganezaki, Osezaki) | East Izu (IOP, Futo) |
| NE wind | East Izu (IOP, Futo) | West Izu (Koganezaki) |
| S wind | Sea of Japan (Echizen, Tajiri) | Pacific coast generally |
| W wind | East Izu (IOP, Futo) | West Kii Peninsula |
Final Check with AI Forecast
Once you've narrowed to 2–3 candidate sites, check the AI visibility forecast on this site for your final decision. The AI forecast combines weather data, satellite data, and historical trends to predict visibility for each site.
AI Forecast Strengths
- Accounts for rainfall and wave impact
- Uses satellite chlorophyll data
- Learns site-specific historical patterns
AI Forecast Limitations
- Sudden current changes hard to predict
- Less accurate at low-data sites
- Numbers are guides; expect ~5m margin
Quick Decision Tree
Winter (Dec–Feb) ->
Pacific coast is the primary pick. NW wind days: West Izu (Koganezaki, Osezaki). W-SW wind days: East Izu (IOP, Futo). Drysuit recommended.
Spring (Mar–May) ->
Okinawa or Koganezaki. Mainland Pacific suffers spring plankton bloom. For Golden Week travel, Kerama or Ishigaki are reliable. Budget option: Koganezaki (less affected by spring murk).
Summer (Jun–Aug) ->
Islands (Yonaguni, Ishigaki, Kerama) or Sea of Japan (Echizen, Tajiri). Pacific coast warms up with plankton bloom. Obon holiday: Kerama is classic but crowded. Hidden gem: Echizen.
Autumn (Sep–Nov) ->
October is the annual best. Both Pacific coast and islands in great shape. Mikomoto, Kushimoto, Hachijojima recommended. Always check typhoon forecasts — 2-3 days after a typhoon can actually be a chance (site-dependent).
Summary: Data-Driven Dive Planning
- Use the seasonal matrix to narrow the area (most reliable)
- Use the wind guide for specific sites (check day before or day of)
- Use AI forecast for final decision (pick the best from your candidates)
Making these 3 steps a habit significantly reduces the chance of arriving to find murky water. Data isn't perfect, but combined with experience, it meaningfully improves dive satisfaction.
About the Data
The seasonal matrix and wind guide are based on statistical analysis of 46,000+ real visibility observations. Recommended sites are selected by evaluating both average visibility and stability (low variance). Adjust based on your personal diving style and access convenience.
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