| Isojärvi | |
| Pushpin Map: | Finland |
| Location: | Kuhmoinen, Jämsä |
| Coords: | 61.7°N 25.0417°W |
| Basin Countries: | Finland |
| Elevation: | 118.9m (390.1feet) |
Isojärvi is a lake in Finland. It is situated in the municipality of Kuhmoinen and for a lesser part in the municipality of Jämsä in the Central Finland region. The lake is a part of the Kymijoki basin and drains into the lake Päijänne. The Isojärvi National Park is located by the lake.