For the unincorporated community of the same name in Adams County, Washington, see Keystone, Washington (Adams County).

Keystone is a small unincorporated community on Whidbey Island near the Washington State Ferries dock to Port Townsend, in Island County. It is located about 3 miles due south of Coupeville near Fort Casey State Park and Ebey's Prairie National Historic Preserve.

Island County, Washington | Unincorporated communities in Washington