| Triangle Lake | |
| Location: | northwestern Ontario |
| Coords: | 49.8367°N -93.5732°W |
| Type: | Glacial |
| Inflow: | One Unnamed Creek |
| Outflow: | none |
| Pushpin Map: | Ontario |
| Pushpin Map Alt: | Location in Ontario, Canada |
| Basin Countries: | Canada |
| Length: | 600m (2,000feet) |
| Width: | 250m (820feet) |
| Shore: | 2.531km (01.573miles) |
| Frozen: | Only in winter |
| Islands: | none |
| Cities: | none |
Triangle Lake is a very small lake in northwestern Ontario, Canada. It is located between Dryden and Kenora, Ontario. It can be seen from the Trans-Canada Highway on the north side. In late June, 2009, it was the site of road construction. Triangle lake has recently been discovered to be acidified. It is a major concern.