| Fern Lake | |
| Coords: | 40.3367°N -105.6764°W |
| Basin Countries: | United States |
| Pushpin Map: | Colorado#USA |
| Pushpin Map Alt: | Location of Fern Lake in Colorado, USA. |
Fern Lake is an alpine lake in Larimer County, Colorado, United States. It is a major source for the Big Thompson River.