In the above map the blue and white tones show relative ocean depths, from shallowest (white) to deepest (dark blue).
The Strait of Georgia lies between Vancouver Island and the British Columbia mainland. The Canada-US border runs through the southern part of the Strait.
To the south, Georgia Strait adjoins Puget Sound (which extending to near the bottom of the map) and to the west, it adjoins Haro Strait, then the Strait of Juan de Fuca (bisected by the order).
This map was originally published by the BC-Washington Marine Science Panel, appointed in 1993 to study the key environmental issues facing the shared waters in the transboundary region. The Marine Science Panel's report was published in 1994 and led to a number of actions by government agencies. More info.
This map shows more of the Strait's adjoining waters, along with the topography (land elevations) of Vancouver Island and the mainland coast of British Columbia and Washington State.
The Strait of Georgia is about two-thirds the length of Vancouver Island, running from its southern tip, north to where its waters narrow to almost meet the mainland coast. This northern area is choked with small islands and rapid tidal passages. Beyond that point, Johnstone Strait stretches northwest to meet Queen Charlotte Strait, then the open Pacific Ocean.
Georgia Strait, Puget Sound and the Strait of Juan de Fuca are together known as the Salish Sea, in recognition of the Coast Salish peoples who have lived in this region for millenia.
Thanks to People for Puget Sound for map.