McMicken Island State Park is a marine park in Case Inlet on the east side of Harstine Island in South Puget Sound, Washington. It spans 222 acres, including the 11.5-acre forested McMicken Island and 1,661 feet of saltwater shoreline around a sheltered cove. A defining feature is the tombolo, a sand bar that connects McMicken Island to Harstine Island at low tide, giving the park its distinctive mix of shoreline and island landscape. The area supports hiking, boating, and shellfish harvesting, and the park is administered as a satellite of Jarrell Cove State Park. Its name honors William C. McMicken, Washington Surveyor General from 1873 to 1886.