Skagit Island Marine State Park, Marine park in Skagit County, Washington, US.

Skagit Island Marine State Park is a 25-acre island in Puget Sound featuring coastal forests, open meadows, and exposed rock formations along sandy shorelines. The park spans diverse terrain with areas of dense vegetation and natural landscape features typical of the Pacific Northwest coast.

Skagit Island became a Washington state park; the state's marine park system was created in 1969, and the island is one of its boat-only units in Skagit Bay, a mile east of Hoypus Point. The 25-acre island lies within the range of Deception Pass State Park's waters, and camping is permitted on the island.

The island serves as a stop for paddlers and sailors following the Cascadia Marine Trail, attracting water-based travelers seeking sheltered camping grounds. It has become a gathering point for people exploring Puget Sound from the water, shaped by the traditions of coastal exploration and self-powered watercraft journeys.

Skagit Island lies in Skagit Bay, one mile east of Hoypus Point and 1.5 miles east of Cornet Bay in Deception Pass State Park; it can be reached only by boat, with no road or bridge link. Camping is permitted on the island, which measures about 495 m by 266 m. Bring your own drinking water, as the sources list no water supply on the island.

Skagit Island measures roughly 495 metres long and 266 metres wide, and camping is permitted on it. The island lies one mile east of Hoypus Point and 1.5 miles east of Cornet Bay, so boaters crossing Skagit Bay can judge the distance to the mainland from the water.