| Lac de Castet | |
| Location: | Pyrénées, Pyrénées-Atlantiques |
| Coords: | 43.0714°N -0.4189°W |
| Type: | reservoir |
| Inflow: | Gave d'Ossau |
| Pushpin Map: | Pyrenees |
| Basin Countries: | France |
| Length: | 1.2km (00.7miles) |
| Width: | 0.44km (00.27miles) |
| Area: | 0.4km2 |
| Elevation: | 423m (1,388feet) |
| Islands: | numerous islets |
Lac de Castet is a lake in Pyrénées, Pyrénées-Atlantiques, France. At an elevation of 423 m, its surface area is 0.4 km².