The Salish (SAY-lish) Sea describes the coastal waterways from the south-western tip of the Canadian province of British Columbia, and the north-western tip off Washington state. It includes the waters around and between the San Juan Islands which Orcas Island is a part of.
Salish, really refers to a common language spoken between tribes. The Coast Salish people and the Interior Salish are the main two in the Salish family. The Coast Salish peoples are indigenous to this area. However, the Interior Salish who reside in Montana, were the first people from the Salishan family that were met and documented by, Lewis and Clark in the early 19th century.
Interestingly the term, Salish Sea was first coined in 1988 by a marine biologist. Before then only the people were referred to as, Salish. So actually its relatively new!