It is located on the south shore of the Saint Lawrence River halfway between Quebec City and Rivière-du-Loup.

The Musée Maritime du Québec (Quebec Marine Museum) is located there on Route 132.

The municipality got its name from a small island in the river near the village of L'Islet-sur-Mer.

The Notre-Dame-de-Bonsecours church, built 1768, is classified as important historical building.

The town hosts many small events during the year such as the Festival Guitares en fête, La Parades des Berlots, and the L'Islet Car Show.