Posey Island Marine State Park

Posey Island Marine State Park is a small, one-acre marine camping park with 1,000 feet of shoreline. It is located a quarter mile north of Pearl Island, near Roche Harbor, San Juan Island. Posey Island is part of the Cascadia Marine Trail. All onshore campsites are for the exclusive use of boaters arriving by human- or wind-powered watercraft.
  1. Activities
  2. Boating
  3. Camping

Picnic & Day-Use Facilities


Visitors arriving by vessels with motorboats are not permitted to camp at the park, but may use the island for day use. There is no potable water or garbage service to the island. Visitors must pack out what they pack in. There is one composting toilet.