High Quality Content by WIKIPEDIA articles! The Puget Sound region is an inland area of the Pacific Northwest in Washington (State), including Puget Sound, the Puget Sound lowlands, and the surrounding region roughly west of the Columbia Basin and east of the Olympic Mountains. 15,000 years ago Seattle was under 3,000 feet (910 m) of ice. 11,000 B.P. Before that, the Puget Sound region was smashed together by shifting tectonic plates. By the time Captain George Vancouver found the Sound, early native people had already been there for over 5,000 years.