Puget Sound is deep by estuarine standards, but if we look north into the Strait of Georgia we can find waters up to 650 m. If the tallest building in Seattle, the Columbia Center, had been built on this spot just 1 m would be visible above the water’s surface at low tide. The deepest spot in the Sound, offshore of Point Jefferson in Main Basin, is 286 m. Depthīecause of its glacial origins the Sound is deep, averaging 70 m, compared to an average of just 6 m for the shallow, muddy Chesapeake. Note: this distance refers to Puget Sound proper and does not include the San Juan Islands or the Strait of Juan de Fuca. It would take about 18 days to walk the whole shoreline if it were passable-or legal-everywhere. The coastline around Puget Sound is 2,143 km (1,332 miles) long. The length of an estuarine channel can be a region where ocean and river water mix, creating a gradual salinity variation to which the biology must adapt. The Chesapeake is about 322 km long, and San Francisco Bay, a West Coast drowned river valley is 97 km long. 2Ĭhesapeake Bay, the largest estuary on the East Coast, is an example of a drowned river valley. We refer here to all such systems as estuaries, loosely defined as any bay or channel off of the ocean that is influenced by rivers and tides. At lower latitudes the most common estuarine type is a drowned river valley, meaning that the estuarine channel was originally a river valley that has since been filled in by the ocean as sea level has risen about 120 m since the Last Glacial Maximum. Because of their glacial origins these systems are sometimes called fjords, and have much in common with other high latitude estuaries in both hemispheres.

Long Island Sound, also carved by glaciers, is similar to Puget Sound at 182 km. Puget Sound is about 161 km in length, going from Admiralty Inlet to Olympia. The circulation patterns are a consequence of the shape of the Sound and the interaction of tides and rivers. The Sound has remarkable patterns of water circulation that support its thriving ecosystem, and which give rise to water quality problems such as hypoxia. The deep and complex troughs that make up Puget Sound were carved by glaciers, most recently about 10,000 years ago.

1 It is part of the Salish Sea, a larger system of inland marine waters that includes the Strait of Georgia and the Strait of Juan de Fuca. Oceanographers define Puget Sound as the region of marine and brackish waters extending landward from Admiralty Inlet.

Puget sound light phenomena