Manta Season Visibility: When to Dive Ishigaki & Yonaguni for Mantas + Clear Water
2026-03-11
"I want to see mantas, and I also want clear water" — every diver's wish. We analyzed actual visibility data from 6,300+ real observations during Ishigaki's manta season (Oct–May) and Yonaguni's hammerhead season (Jan–Mar). The conclusion is surprisingly optimistic: big animal season does not mean poor visibility — in fact, it stays consistently high.
Ishigaki Monthly Visibility & Water Temp (1,473 obs total)
Manta season at Ishigaki's famous Manta Scramble runs roughly Oct–May. The site maintains 19–22m visibility year-round.
| Month | Vis (m) | Temp (°C) | Obs | Mantas |
|---|---|---|---|---|
| Jan | 20.9m | — | 27 | ◉ |
| Feb | — | — | — | ◉ |
| Mar | 21.9m | — | 96 | ◉ |
| Apr | 21.2m | 20.8°C | 106 | ◉ |
| May | 20.1m | 26°C | 136 | ◉ |
| Jun | 20.1m | — | 151 | ○ |
| Jul | 20.9m | 27°C | 197 | ○ |
| Aug | 21m | 26°C | 212 | ○ |
| Sep | 21.4m | — | 176 | ○ |
| Oct | 19.4m | 26.5°C | 184 | ◉ |
| Nov | 19.1m | 26°C | 134 | ◉ |
| Dec | 19.4m | — | 54 | ◉ |
◉=manta season (high encounter rate) Feb: no data available Some months lack temp data
Key Finding: Manta Season Has Excellent Visibility
- Average visibility during manta season (Oct–May): 20.6m
- Best month: March at 21.9m — coincides with peak manta season
- Lowest month (November) is still 19.1m — impossible to find near Tokyo
- Summer average (Jul–Sep): 21.1m — nearly identical to manta season (20.6m)
Yonaguni Monthly Visibility & Water Temp (4,826 obs total)
Yonaguni's hammerhead sharks (and huge schools of bigeye trevally) appear mainly Jan–Mar. Here's what the real visibility data shows for that period.
| Month | Vis (m) | Temp (°C) | Obs | Hammers |
|---|---|---|---|---|
| Jan | 22.4m | 24°C | 476 | ◉ |
| Feb | 22.6m | 23.8°C | 424 | ◉ |
| Mar | 23.5m | 24.2°C | 435 | ◉ |
| Apr | 23.9m | 25°C | 401 | ○ |
| May | 24.2m | 26.3°C | 416 | ○ |
| Jun | 24.4m | 27.6°C | 347 | ○ |
| Jul | 25.6m | 28.6°C | 444 | ○ |
| Aug | 26.5m | 28.7°C | 402 | ○ |
| Sep | 27.3m | 28.6°C | 373 | ○ |
| Oct | 26.8m | 27.8°C | 289 | ○ |
| Nov | 24.4m | 26.4°C | 339 | ○ |
| Dec | 23.4m | 25.2°C | 480 | ○ |
◉=Hammerhead shark appearance season (approximate)
Key Finding: Hammerhead Season Also Has High Visibility
- Average visibility during hammerhead season (Jan–Mar): 22.8m
- March: 23.5m (best). January: 22.4m (lowest) — still exceptional
- Water temp 24.0–24.2°C — comfortable in a 3mm wetsuit (slightly cool)
- Caution: Yonaguni visibility is highly variable day-to-day (AI R²=0.046). Could be 24.5m or 15m
Big Animal Season × Visibility Summary
Manta Season (Ishigaki)
Oct–May (peak Dec–Mar)
Highest encounter rates at Manta Scramble. Visibility holds at 19–22m.
Hammerhead Season (Yonaguni)
Jan–Mar
Schools of hammerhead sharks appear. Visibility 22–24m: excellent.
Summer (ref) Ishigaki
Jul–Sep
Fewer mantas but stable visibility. Rich coral reefs and pelagics.
Winter Diving: Gear & Wetsuit Notes
| Period & Site | Water Temp | Recommended Suit | Notes |
|---|---|---|---|
| Ishigaki Dec–Mar | 21–24°C | 5mm wetsuit | Multiple dives may feel cool |
| Yonaguni Jan–Mar | 24.0–24.2°C | 3–5mm wetsuit | Personal preference |
| Ishigaki Jul–Sep (summer) | 26–27°C | 3mm wetsuit | Rash guard option |
| Yonaguni Jul–Sep (summer) | 28.6–28.7°C | 3mm wetsuit | Most comfortable + clearest |
Average vs. Reality: The Yonaguni Caveat
Yonaguni's visibility varies dramatically day-to-day
The monthly average of 22.4–23.5m during Jan–Mar looks great, but the AI's low predictability score (R²=0.046) shows day-to-day visibility is nearly random. Some days exceed 30m; others drop to 15m.
Ishigaki (prediction accuracy not calculated due to data gaps) also has day-to-day variability despite consistent seasonal patterns. We strongly recommend checking local dive shop blogs the day before your trip.
Best Timing Guide: Mantas + Clear Water
Ishigaki: March–April is Peak
- March: 21.9m (best clarity) + high manta encounter
- April: 21.2m + 20.8°C (5mm wetsuit)
- January: 20.9m. Perfect for New Year's diving (cold but clear)
Yonaguni: March is the Sweet Spot
- March: 23.5m (best of Jan–Mar) + hammerhead season
- Water temp 24.2°C — warmer and more comfortable than Ishigaki
- High day-to-day variability — always check dive shop updates
About the Data
Ishigaki: 1,473 observations (some months have no data or missing water temp). Yonaguni: 4,826 observations. Compiled from dive shop daily logs 2015–2026. Manta/hammerhead presence information is based on general dive shop guidance (not directly measured). All visibility values are averages of real observations.
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