Lake of Two Mountains (French: Lac des Deux Montagnes) is part of the river delta widening of the Ottawa River in Quebec, Canada, at its confluence with the St. Lawrence River.

Lake of Two Mountains
Lac des Deux Montagnes (French)
Île aux Tourtes Bridge across Lake of Two Mountains, with Mont Oka in the background
Location map of Lake of Two Mountains
Lake of Two Mountains
Location	Deux-Montagnes RCM / Vaudreuil-Soulanges RCM / Montreal, Quebec
Coordinates	45°27′N 74°00′W / 45.450°N 74.000°W / 45.450; -74.000
Primary inflows	Ottawa River
Primary outflows	Rivière des Mille Îles, Rivière des Prairies
Basin countries	Canada

Lake of Two Mountains has four outflows: Rivière des Mille Îles and Rivière des Prairies, bordering Île Jésus, and two branches of the Ottawa River, flowing into the St. Lawrence via Lake Saint-Louis, on either side of Île Perrot.

The city of Deux-Montagnes is located on the lake's north shore, where it flows into Rivière des Mille Îles. The southwest portion of the city of Montreal borders the eastern part of the lake, as does the village of Senneville. Kanesatake (Kanehsatà:ke), a Kanien'kéha:ka Mohawk reserve in Kanesatake, Quebec, is also located along the northern shore.