| Fern Lake | |
|---|---|
| | |
| Location | Rocky Mountain National Park, Larimer County, Colorado, US |
| Coordinates | 40°20′12″N105°40′35″W / 40.33667°N 105.67639°W |
| Primary outflows | Big Thompson River |
| Basin countries | United States |
Fern Lake is an alpine lake in Larimer County, Colorado, United States. It is a major source for the Big Thompson River.