| Mainstay Lake | |
|---|---|
 | |
  Mainstay Lake  Mainstay Lake | |
| Location | South America |
| Coordinates | 07°13′59″N 58°32′19″W / 7.23306°N 58.53861°W |
| Basin countries | Guyana |
| Max. length | 193 mi (311 km) |
| Max. width | 53 mi (85 km) |
| Surface area | 7,540 sq mi (19,500 km2) |
| Average depth | 283 ft (86 m) |
Mainstay Lake is a lake in the Pomeroon-Supenaam Region of Guyana, near the Atlantic coast, northwest of the mouth of the Essequibo River, 12 mi (19 km) north of Adventure. There is a 0.5 mi (0.80 km) stretch of white sand at the edge of the lake.