Gedney Island (also known as Hat Island) is an island in Possession Sound in Snohomish County, Washington. The populated community of Hat Island is located on the island and has 41 people as of the 2010 census.
Gedney Island was first mentioned in the historical record by naturalist Archibald Menzies of the Vancouver Expedition in 1792. It was named by Charles Wilkes in 1841, possibly for New York politician John B. Gedney.
There is currently one walk-on ferry named the Hat Express which transports walk-on passengers to and from the island. The maximum capacity of the ferry is 88 passengers. It runs a limited schedule on Wednesdays, Fridays and weekends between the Everett Yacht Club on the west end of 13th Street in Everett, and the Hat Island Marina.