Sainte-Marthe-sur-le-Lac (French pronunciation: [sɛ̃t maʁt syʁ lə lak], lit.

It is crossed from east to west by Route 344, commonly known as Oka Road.

The town shares its borders with Deux-Montagnes to the east, Saint-Joseph-du-Lac to the west, the Lake of Two Mountains to the south, and Saint-Eustache to the north.

It was formerly known as a rural town in which most of its inhabitants were seasonal vacationers, but it is increasingly lived in year-round.

[5] Population trend:[6] Mother tongue: The Commission scolaire de la Seigneurie-des-Mille-Îles (CSSMI) operates Francophone schools.