Japan's Top 5 Clearest Dive Sites Outside Okinawa — Real Data Ranking
2026-03-11
Real-data visibility ranking for non-Okinawa/Yakushima sites. #1 Hachijojima at 17.2m.
Answering "Where's Clearest Outside Okinawa?" with Real Data
Everyone knows Yonaguni and Kerama are Japan's clearest dive sites. But what about the rest of Japan? This ranking covers sites outside Okinawa and Yakushima with at least 100 observations in our 46,000-entry database.
Top 5 Rankings
| Rank | Site | Annual Avg. | Best Month | Observations |
|---|---|---|---|---|
| #1 | HachijojimaTokyo | 17.2m | Sep (21.9m) | 326 |
| #2 | Ito (Tateyama)Chiba | 15.9m | Jan/Dec (18–18.8m) | 1,981 |
| #3 | ShirahamaWakayama | 14.9m | Dec–Jan (17–18m) | 616 |
| #4 | Akinohama (Izu Oshima)Tokyo (Izu Oshima) | 14.3m | Jan/Dec (15.1m) | 1,309 |
| #5 | IOP (Izu Oceanic Park)Shizuoka | 13.8m | Jan (18.6m) | 3,151 |
#1 Hachijojima (Tokyo) — 17.2m average
Southernmost Izu Island volcanic peak. Direct Kuroshio influence, high clarity year-round.
#2 Ito (Tateyama) (Chiba) — 15.9m average
Kanto region's clearest site. Peaks in winter; famous for large sharks. ~1.5h from Tokyo.
#3 Shirahama (Wakayama) — 14.9m average
Kuroshio-influenced Nanki resort diving. Clear winters, warm summers.
#4 Akinohama (Izu Oshima) (Tokyo (Izu Oshima)) — 14.3m average
Annual swing just 1.5m — Japan's most stable site. ~1.75h by fast ferry from Takeshiba.
#5 IOP (Izu Oceanic Park) (Shizuoka) — 13.8m average
Most data of any site (3,151 obs). AI prediction accuracy 82% — Japan's best. Famous for winter clarity.
Monthly Visibility Data for Key Sites
Hachijojima Monthly Visibility
| Month | Avg. Visibility | Avg. Temp. |
|---|---|---|
| Jan | 17.4m | 18.9°C |
| Feb | 16.9m | 18.1°C |
| Mar | 15.4m | 18.8°C |
| Apr | 15m | 19.8°C |
| May | 19.8m | 21.3°C |
| Jul | 13.6m | 20.5°C |
| Aug | 17.3m | 24.5°C |
| Sep | 21.9m | 27.1°C |
| Oct | 16.4m | 26.7°C |
| Nov | 16.9m | 23.7°C |
| Dec | 16.8m | 22°C |
Ito Monthly Visibility
| Month | Avg. Visibility | Avg. Temp. |
|---|---|---|
| Jan | 18.8m | 16.7°C |
| Feb | 17.4m | 16.1°C |
| Mar | 16.4m | 15.8°C |
| Apr | 14.8m | 16.1°C |
| May | 15.9m | 16.9°C |
| Jun | 15.7m | 18.6°C |
| Jul | 13.2m | 19.7°C |
| Aug | 15m | 20.5°C |
| Sep | 14.7m | 22.3°C |
| Oct | 15.8m | 22.6°C |
| Nov | 15m | 21.1°C |
| Dec | 18.7m | 18.4°C |
Akinohama Monthly Visibility
| Month | Avg. Visibility | Avg. Temp. |
|---|---|---|
| Jan | 15.1m | 16.8°C |
| Feb | 14.9m | 16.5°C |
| Mar | 14.1m | 16.3°C |
| Apr | 13.6m | 16.6°C |
| May | 13.4m | 17.5°C |
| Jun | 14.1m | 19°C |
| Jul | 13.8m | 20.3°C |
| Aug | 13.8m | 22.4°C |
| Sep | 14.9m | 23.8°C |
| Oct | 14.9m | 23.2°C |
| Nov | 14.5m | 21.5°C |
| Dec | 15.1m | 18.7°C |
IOP (Izu Oceanic Park) Monthly Visibility
| Month | Avg. Visibility | Avg. Temp. |
|---|---|---|
| Jan | 18.6m | 16.8°C |
| Feb | 17.7m | 16°C |
| Mar | 13.7m | 16°C |
| Apr | 10.1m | 16.5°C |
| May | 10.6m | 17.8°C |
| Jun | 11.3m | 20°C |
| Jul | 11.6m | 21.5°C |
| Aug | 12.3m | 23.4°C |
| Sep | 12.7m | 24.2°C |
| Oct | 13.7m | 23.9°C |
| Nov | 14.7m | 21.7°C |
| Dec | 17.3m | 19°C |
Summary: Best Choices Outside Okinawa
- Highest visibility: Hachijojima (17.2m avg) — September peak 21.9m
- Best near Tokyo: Ito/Tateyama (Chiba, 15.9m) — 1.5h drive, peaks in winter
- Most stable: Akinohama/Izu Oshima (14.3m) — minimal seasonal swing
- Most data, best AI accuracy: IOP (13.8m) — January peak 18.6m
- Nanki resort: Shirahama (Wakayama, 14.9m) — Kuroshio-touched
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