Posey Island is a one-acre marine campsite in the San Juan Islands accessible only by human-powered watercraft (kayak, canoe), featuring two primitive Cascadia Marine Trail campsites with fire rings, picnic tables, and a composting toilet—no potable water available.

Reservations are required and must be booked at least two weeks in advance (up to nine months ahead) through washington. goingtocamp. com, with a maximum of 16 people per night and 3-night stay limit.

The island offers excellent wildlife viewing opportunities including orca whales, seals, and porpoises, plus spectacular sunset views, making it a popular paddling destination near Roche Harbor on San Juan Island.