| Lake Ermistu Ermistu järv | |
| Pushpin Map: | Estonia |
| Location: | Ermistu, Pärnu, Pärnu County, Estonia |
| Lake Type: | Eutrophic |
| Outflow: | Tõstamaa River |
| Catchment: | 32.3km2 |
| Basin Countries: | Estonia |
| Length: | 4070m (13,350feet) |
| Width: | 1750m (5,740feet) |
| Area: | 449.5ha |
| Depth: | 1.3m (04.3feet) |
| Max-Depth: | 2.9m (09.5feet) |
| Shore: | 19.5451NaN1 |
| Islands: | 14 |
Lake Ermistu (et|Ermistu järv; also known as Lake Tõstamaa) is a 449.5ha[1] lake in southwestern Estonia. Administratively it belongs to the Ermistu village in Pärnu municipality, Pärnu County.