<P> Anderson Island is the southernmost island in Puget Sound and a census - designated place of Pierce County, Washington, United States . It is accessible by boat or a 20 - minute ferry ride from Steilacoom . Anderson Island lies just south of McNeil Island . To the northwest Key Peninsula lies across Drayton Passage . The south basin of Puget Sound separates the island from the mainland to the southeast, while to the southwest the Nisqually Reach of Puget Sound separates the island from the mainland . </P> <P> Anderson Island has a land area of 7.75 square miles (20.1 km), and reported a population of 1,037 persons as of the 2010 census . The island had been a retirement destination since the late 1960s, with a median age of 54 years (for comparison, the median age of Washington state as a whole is 37 years). The population booms every summer to approximately 4,000 . The Island is also home to a sizable population of deer . </P>

How do you get to anderson island wa