Doe Island Marine State Park, Marine park in San Juan County, United States.

Doe Island Marine State Park covers all 6.11 acres of Doe Island in the San Juan Islands, San Juan County, Washington, about 0.25 miles (0.40 km) southeast of Orcas Island, with 2,049 feet (625 m) of shoreline. A 0.3-mile trail circles the island, and five first-come campsites with fire rings, picnic tables and a vault toilet sit on the island; there is no potable water or electricity.

Washington State Parks bought part of Doe Island from the Bureau of Land Management in 1964 for $15.27. A second parcel was acquired from the Department of Natural Resources in 1967 at no cost, completing public ownership of the 6.11-acre island.

Visitors harvest oysters and crabs from the surrounding waters, activities the park explicitly permits. The island's name, shared with Doe Bay on nearby Orcas Island, ties it to the San Juan Islands' English place-name tradition. A 0.3-mile trail circles the shore, passing tidal zones where shellfish beds are visible at low tide.

Doe Island lies about a quarter mile southeast of Orcas Island and has no dock in service, so boaters must land without one. The island has no potable water or electricity; bring drinking water and supplies. Five campsites with fire rings, picnic tables and a vault toilet are first-come, first-served, with no reservations.

The island sits just a short distance from a much larger neighbor, allowing visitors to move quickly between two very different environments on the water. This proximity makes it a convenient stop for boaters exploring the broader region.