Steamboat Island is an island in southern Puget Sound. Located at the opening of the Totten Inlet, the area lies at the northern end of a peninsula known locally as the "Steamboat Peninsula".
Founded in 1909, Steamboat Island was named by local settlers who thought the island resembled a steamboat. The peninsula and island are contained within the Griffin School District and is served by the Griffin Fire Department #13 and is also known locally as the "Griffin area" of Thurston County, Washington.
The population is mostly Caucasian and largely made of two person households.
The island is about due west from Hope Island Marine State Park, which is accessible only by boat.