Of all the Monteregian Hills that rise so prominently from the floor of the St. Lawrence River Valley, Mont St. Hilaire (414 m) is the least disturbed by human activity and the richest in terms of natural history and cultural interest. Lac Hertel (32 hectares), surrounded by the only remaining primeval forests in the region, forms the heart of the mountain.
The mountain, clothed in virgin forest, is an exceptional locality for both plant and animal diversity.
There are over 600 higher plant species on the mountain, including many species designated rare or endangered in Quebec and Canada. Some trees in the forest exceed 400 years of age. There are over 800 known species of butterflies and moths on the mountain and its surroundings.
The unusual geology of the mountain fully equals the richness of its biological resources. Mont St. Hilaire is recognized as among the top ten mineral-collecting sites in the world. There are 372 known types of minerals on the mountain, of which 50 are new to science. Others have been collected but remain of uncertain identity.
Mont St. Hilaire also occupies a special place in the cultural history of Quebec and Canada through its influence on the work of Ozias Leduc, an artist who lived and worked at the foot of the mountain. Paul Émile Borduas, a student of Leduc, also lived in the region for a couple of years. For more information, visit the Musée d'art de Mont-Saint-Hilaire
The great scientific and cultural significance of Mont St. Hilaire was recognized in 1978 when the United Nations designated the mountain as the first Canadian site in the UNESCO Biosphere Reserve program. The mountain is also recognized as a migratory bird sanctuary and is in the process of being designated a sanctuary for the peregrine falcons that nest on the Dieppe Cliffs.