Olga Lake is a freshwater body crossed by the Waswanipi River and located in the southern part of Eeyou Istchee James Bay (municipality), in administrative region of the Nord-du-Québec, in the province of Quebec, in Canada.

[1] The Olga Lake hydrographic slope is accessible via the James Bay Highway coming from the southwest (from Matagami), then branches northward by cutting the Canet River at the north of Lake Olga.

The surface of Olga Lake is usually frozen from early November to mid-May, however, safe ice circulation is generally from mid-November to mid-April.

Lake Olga also obtains supplies from the Southeast via the Opaoca River (via Elisabeth Bay), a creek from the Southwest, and the discharge (from the Northwest) of Lakes Caron and Gabrielle.

[3] The toponym "lac Olga" was formalized on December 5, 1968, by the Commission de toponymie du Québec, when it was created.