Clearest lakes in Switzerland
Clearest lakes in Switzerland: 18 named lakes have an official Secchi depth. The 18 below are ranked by that reading — water clarity, not a LakeQuality A–F grade.
Lake map
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Highest Secchi readings in Switzerland
| Lake | Place | Total phosphorus | Chlorophyll-a | Secchi | Year |
|---|---|---|---|---|---|
| Lake Thun | Bern | — | — | 8.2 m | 2023 |
| Lake Neuchâtel | Neuchâtel | — | — | 8.0 m | 2023 |
| Lake Maggiore | Ticino | — | — | 7.3 m | 2023 |
| Walensee | St. Gallen | — | — | 7.1 m | 2023 |
| Lake Geneva | Vaud | — | — | 7.0 m | 2023 |
| Lake Lugano | Ticino | — | — | 6.0 m | 2023 |
| Lake Constance | Thurgau | — | — | 5.8 m | 2023 |
| Lake Biel | Bern | — | — | 5.2 m | 2023 |
| Lake Zug | Zug | — | — | 5.0 m | 2023 |
| Lake Zürich | Zürich | — | — | 4.9 m | 2023 |
| Hallwilersee | Aargau | — | — | 4.4 m | 2023 |
| Lake Brienz | Bern | — | — | 4.2 m | 2023 |
| Lake Murten | Fribourg | — | — | 4.0 m | 2023 |
| Sempachersee | Lucerne | — | — | 3.9 m | 2023 |
| Greifensee | Zürich | — | — | 3.4 m | 2023 |
| Pfäffikersee | Zürich | — | — | 3.3 m | 2023 |
| Lac de Joux | Vaud | — | — | 3.2 m | 2023 |
| Baldeggersee | Lucerne | — | — | 2.9 m | 2023 |
Frequently asked questions
- Which lakes in Switzerland are the clearest?
- 18 named lakes in Switzerland have an official Secchi depth. This page ranks the 18 deepest readings. Secchi is a clarity measurement, not a swim-safety class and not a LakeQuality A–F grade.
- 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 grade. Open a lake page for the authority's values.
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