From river to estuary to gulf, the St. Lawrence covers nearly 2,000 kilometers between the Great Lakes and the Atlantic Ocean. A simple freshwater flow at its source, it swells with the waters of countless tributaries as it races to complete a giant course toward the open sea. Its unique blend of fresh, brackish and salt waters shelters thousands of species of plants, invertebrates, fishes, birds and mammals. Between the surface of the St. Lawrence and its most intimate abysses, within its depths and along its shores, unfold an ever-changing universe of life and colour.This carefully laid-out book pays tribute to one of the richest natural heritages of North America. It explores a succession of freshwater and marine habitats amidst which flourishes a diversified flora and fauna. Abundant photographs reveal contrasting landscapes, familiar and strange animals, as well as luxuriant terrestrial and aquatic vegetation.