Whidbey Island (historical spellings Whidby, Whitbey, or Whitby) is the largest of the islands composing Island County, Washington, in the United States, and the largest island in Washington state. Whidbey is about 30 miles (48 km) north of Seattle, and is separated from the Olympic Peninsula in the southwest by Admiralty Inlet. The island forms the northern boundary of Puget Sound. It is home to Naval Air Station Whidbey Island. The state parks and natural forests are home to numerous old growth trees.
As of the 2020 U.S. census, Whidbey Island has 69,501 total residents. The majority live in the center of the island, which includes its most populous city, Oak Harbor.