| Boontsagaan Lake | |
| Location: | Bayakhongor |
| Coords: | 45.55°N 103°W |
| Basin Countries: | Mongolia |
| Length: | 24km (15miles) |
| Width: | 11km (07miles) |
| Pushpin Map: | Mongolia |
| Area: | 252km2 |
| Depth: | 9.3m (30.5feet) |
| Max-Depth: | 16m (52feet) |
| Elevation: | 1312m (4,304feet) |
Böön Tsagaan Lake (Mongolian: Бөөн Цагаан нуур) is a large saline lake in Bayakhongor province in the Gobi Desert of southern Mongolia.
Böön Tsagaan Lake and the nearby Taatsiin Tsagaan Lake, Adgiin Tsagaan Lake, and Orog Lake, are collectively designated a Ramsar wetland of international importance under the name "Valley of the Lakes".