In this spectacular documentary, Jacques-Yves Cousteau, oceanographer, and an NFB-Cousteau crew sail up the St. Lawrence River to the Great Lakes on board the specially equipped vessel, the Calypso. They explore the countryside from their helicopter and plumb the depths in their diving saucer. Shipwrecks, both historic and more recent, the Manicouagan power dam, Niagara Falls, the St. Lawrence Seaway locks, and an underwater chase with caribou are some of the sights filmed above and below water. What they see is exciting, sometimes dramatic and often disheartening; pollution is taking its toll.