Clearest lakes in Japan
Clearest lakes in Japan: 159 named lakes have an official Secchi depth. The 20 below are ranked by that reading, water clarity as the authority reports it.
Lake map
Map shows 20 lakes with coordinates
Highest Secchi readings in Japan
| Lake | Place | Total phosphorus | Chlorophyll-a | Secchi | Year |
|---|---|---|---|---|---|
| 支笏湖 | Hokkaido | 3.0 µg/L | — | 18 m | 2025 |
| 倶多楽湖 | Hokkaido | 3.0 µg/L | — | 17 m | 2024 |
| 本栖湖 | Yamanashi | 3.0 µg/L | — | 14 m | 2025 |
| 洞爺湖 | Hokkaido | 3.0 µg/L | — | 13 m | 2024 |
| 十和田湖 | Akita | 4.0 µg/L | — | 11 m | 2024 |
| 十和田湖 | Aomori | 4.0 µg/L | — | 10 m | 2024 |
| 猪苗代湖 | Fukushima | 5.0 µg/L | — | 10 m | 2024 |
| 田沢湖 | Akita | 3.0 µg/L | — | 10 m | 2024 |
| 味噌川ダム貯水池 | Nagano | 7.0 µg/L | — | 8.6 m | 2025 |
| 屈斜路湖 | Hokkaido | 6.0 µg/L | — | 8.3 m | 2024 |
| 池田湖 | Kagoshima | 4.0 µg/L | — | 8.0 m | 2025 |
| 中禅寺湖 | Tochigi | 5.0 µg/L | — | 7.8 m | 2024 |
| 芦ノ湖 | Kanagawa | 4.0 µg/L | — | 7.8 m | 2025 |
| 深山ダム貯水池 | Tochigi | 4.0 µg/L | — | 7.3 m | 2024 |
| 沼沢湖 | Fukushima | 4.0 µg/L | — | 6.8 m | 2024 |
| 小河内貯水池 | Tokyo | 8.0 µg/L | — | 6.5 m | 2025 |
| 早明浦ダム貯水池 | Kochi | 5.0 µg/L | — | 6.5 m | 2025 |
| 野尻湖 | Nagano | 5.0 µg/L | — | 6.3 m | 2025 |
| 川俣ダム貯水池 | Tochigi | 7.0 µg/L | — | 6.1 m | 2025 |
| 奥只見貯水池 | Niigata | 5.0 µg/L | — | 6.0 m | 2024 |
Showing 20 of 159 named lakes. Open a county or place page for the rest.
Frequently asked questions
- Which lakes in Japan are the clearest?
- 159 named lakes in Japan have an official Secchi depth. This page ranks the 20 deepest readings. Secchi is a clarity measurement, not a swim-safety class.
- Is clear water the same as clean water?
- No. Secchi measures how far a disk stays visible. A clear lake can still have bacteria, toxins, or contaminants this catalog does not measure. Open a lake page for the authority's values.
Clearest lakes in other countries
Named lakes and official measurements
Directory of official lake water quality
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Where to stay near Japan
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