A delta is a deposit of sediment at the mouth of a river that accumulates as the river flows into a standing body of water such as a lake or ocean. Because sediment tends to be rich in nutrients, deltas become fertile wetlands inhabited by diverse wildlife. Among the largest deltas in Canada are those of the Mackenzie and Saskatchewan rivers, as well as the Peace-Athabasca Delta (where the Peace, Athabasca and Birch rivers meet). Certain deltas offer advantageous access to natural resources and maritime transportation, but development projects are often controversial due to the ecological importance of these environments.
Bonavista Bay is an inlet on the Atlantic coast of Newfoundland between Cape Freels and Cape Bonavista. Roughly 65 km wide, it contains a large number of densely forested islands that shelter the mainland from northeasterly winds and create hundreds of kilometres of virtually landlocked waters.
Canada has the longest coastlines of any country in the world (60 180 km excluding islands, 202 080 including all measurable islands). Canadian coastal waters support valuable biological resources (eg, fish, crustaceans, molluscs, marine mammals and seaweeds) and are important for transportation, recreation and the mineral and hydrocarbon resources in the seafloor beneath them.
Gulf of St Lawrence, a large (250 000 km2), roughly triangular inland sea receiving on average 10 100 m3/s of fresh water from the St Lawrence River at its northwest apex, is connected to the Atlantic by the Strait of Belle Isle at the northeast and Cabot Strait at the southeast corners.