The sea stretches from the channels of the Discovery Islands north of the Strait of Georgia to Budd Inlet at the south end of Puget Sound.

[7] The first known use of the term "Salish Sea" was in 1988 when Bert Webber, a geography and environmental social studies professor emeritus in Huxley College of the Environment at Western Washington University in Bellingham, Washington, created the name for the combined waters in the region with the intention to complement the names Georgia Strait, Puget Sound, and Strait of Juan de Fuca, not replace them.

[9] European and American explorers first encountered Salishan people along the Pacific Northwest coast in the late 18th century.

No overarching title exists for this area or even a commonly shared name for any of the waterbodies in any of the Coast Salish languages.

[16] In March 2008, the Chemainus First Nation proposed renaming the Georgia Strait the "Salish Sea", an idea that reportedly met with approval by British Columbia's Aboriginal Relations Minister Mike de Jong, who pledged to put it before the Executive Council of British Columbia for discussion.

[4] The Transboundary Georgia Basin–Puget Sound Environmental Indicators Working Group defines the limits of the Salish Sea as:[2][3][25] On the West.

The entrance to Juan de Fuca Strait (a line between Cape Flattery and Carmanah Point).

The depression was then carved by the advance and retreat of the Cordilleran Ice Sheet during the Vashon Glaciation, which lasted from about 19,000 – 16,000 BP.

[2][32][33] The Salish Sea supports an active and dynamic marine ecosystem, dominated by species suited to the brackish, nutrient-rich, conditions.

As with all marine food webs, the Salish Sea features a range of trophic groups, with autotrophic algae acting as primary producers.

The fluvial systems draining British Columbia and Washington introduce large volumes of sediment and dissolved nutrients into the Salish Sea.

The Salish Sea hosts a diverse community of kelp species that provide large volumes of high-quality habitat in areas with hard, rocky substrates.

[36] In 2019, this orca population was at a 35-year low after three adult deaths and no surviving calves over three years, leaving only 73 whales in the community.

[41] The mineral-rich waters of the Salish Sea are an ideal habitat for the formation of glass sponge reefs.

[42] Due to their scientific and ecological importance, all known sponge reefs in the Salish Sea are protected from bottom-contact fishing activities.