Île aux Coudres, 30 km2, 11 km long, 4.3 km wide, 92 m high, is situated 60 km downstream from Québec City in the St-Lawrence estuary.
The island consists of 2 Appalachian ridges joined by an embankment.
Their rocky upstream end forms the coves of L'Église and du Havre.
A broad tidal flat surrounds the island. Minor earthquakes are frequent.
In 1535 Jacques Cartier named the island in recognition of its many hazel trees (coudriers).
The island was given as a fief to Étienne de Lessard in 1677, then to the Séminaire of Québec in 1687, and received its first colonists around 1720.
In 1759 it provided moorage for the English flotilla.
The local economy revolves around agriculture, a nearby naval base, peat harvesting and tourism.
References to the once traditional "porpoise" (beluga) fishing industry can be found in the film "Pour la suite du monde" (1963) by Pierre Perrault.