The open water of the Archipelgo is an extremely rich environment and one of the most biologically diverse in the world. The most famous residents of the waters of the San Juan Islands are the orcas, but there is also an abundant sea life population of Dall's porpoise, harbor seals, Stellar sea lions, otters and other marine mammals that feed on salmon and fish that live in these waters. Seabirds that live in the area year round, are winter residents, or visitors that rest and feed during seasonal migration, are always present. The rocky shores also teem with marine life. Harbor seals can be seen here, too, resting on the rocks.
River otters take diving ducks from the surf and small schooling fish from the shallows.
At night mink and raccoons explore the shoreline for food. The tideflats attract birds with a banquet of insects, worms, clams, mussels, tiny crabs and shrimp. These creatures live on the surface or in the mixture of mud, sand and gravel providing food for the top predators of the food chain. Wading birds, plovers, killdeer and sandpipers feed until the flood tide comes in, when seabirds and waterfowl take over. Diving birds such as mergansers, pintails, wigeons, and scaups dive for fish and molluscs.