Puget Sound only Puget Sound proper but also for waters to the north, such as Bellingham Bay and the San Juan Islands region. The term "Puget Sound" is used not just for the body of water but also the Puget Sound region centered on the sound. Major cities on the sound include Seattle, Tacoma, Olympia, and Everett, Washington. Puget Sound is also the third largest estuary in the United States, after Chesapeake Bay in Maryland and Virginia, and San Francisco Bay in northern California. In 1792 George Vancouver gave the name "Puget's Sound" to the waters south of the Tacoma Narrows, in
Puget Sound the ice sheets had retreated. Because the rate of rebound was not synchronous with the post-ice age rise in sea levels, the bed of what is Puget Sound, filled alternately with fresh and with sea water. The upper level of the lake-sediment Lawton Clay now lies about above sea level. The Puget Sound system consists of four deep basins connected by shallower sills. The four basins are Hood Canal, west of the Kitsap Peninsula, Whidbey Basin, east of Whidbey Island, South Sound, south of the Tacoma Narrows, and the Main Basin, which is further subdivided into Admiralty Inlet and the