Posey Island SMP is a public state park in Washington in San Juan County County. The park offers a peaceful retreat into nature for visitors of all ages.
Location & Getting There
Posey Island SMP is located Washington. The park’s coordinates are 48.6183884, -123.1678087.
Things to Do
Washington state parks offer an incredible diversity of outdoor recreation — from the rain-soaked old-growth forests of the Olympic Peninsula to the volcanic landscapes of the Cascades, the arid canyonlands of Eastern Washington, and the island-dotted waters of Puget Sound. Popular activities include hiking through moss-draped temperate rainforests, beachcombing on wild Pacific shores, kayaking through the San Juan Islands, camping beneath towering Douglas firs, fishing for salmon and steelhead in glacier-fed rivers, rock climbing basalt columns, mountain biking forested trails, and cross-country skiing in winter. Many parks also offer historical interpretation, including military forts, pioneer homesteads, and Native American cultural sites.
Best Time to Visit
Washington’s outdoor season varies dramatically by region. Western Washington (including the coast and Puget Sound parks) is driest and warmest from June through September — this is peak season. Spring and fall bring fewer crowds and mild temperatures but expect rain. Eastern Washington parks enjoy more sunshine year-round, with hot summers and cold, snowy winters. The San Juan Islands are best visited May through September for whale watching (orcas) and calm seas. Mountain parks in the Cascades open as snow melts, typically July through October. Winter transforms many parks into cross-country skiing and snowshoeing destinations. Always carry rain gear west of the Cascades, regardless of season.
Visitor Tips
Washington state parks require a Discover Pass ($30/year or $10/day) for vehicle access. Purchase one online through the Washington State Parks website before your visit — it covers all 100+ state parks. Camping reservations are made through the state parks reservation system up to 9 months in advance. Popular parks like Deception Pass and Cape Disappointment book months ahead for summer weekends. Many parks in the San Juans and islands are accessible only by ferry or boat — check Washington State Ferries schedules in advance. Cell service can be unreliable, especially on the coast and in mountain parks.
Frequently Asked Questions
What is a Washington Discover Pass?
The Discover Pass ($30/year or $10/day) is required for vehicle access to all Washington state parks and recreation lands. It can be purchased online, at park entrance stations, or at licensed vendors.
What is the most visited state park in Washington?
Deception Pass State Park on Whidbey Island is the most visited state park in Washington, famous for its dramatic bridge spanning the narrow gorge and stunning views of Puget Sound and the San Juan Islands.
Can I camp on the San Juan Islands?
Yes, several San Juan Islands parks offer camping, including Moran State Park on Orcas Island and Spencer Spit on Lopez Island. Accessible only by Washington State Ferries — book ferry reservations early in summer.
What is the best time to visit Washington state parks?
June through September offers the driest conditions west of the Cascades. The coast can be enjoyed year-round (winter storm watching is popular). Always carry rain gear when visiting parks west of the Cascades.
Explore More Washington State Parks
Posey Island SMP is one of many outstanding state parks in Washington. Discover more parks in our Best State Parks in Washington guide, or use our Park Finder to search by activity, location, or features.
Wildlife & Nature
Posey Island State Marine Park — the formal marine park designation for this 1-acre island near Roche Harbor in the San Juan Islands — provides primitive camping for boaters and kayakers. The surrounding waters support orca whales, harbor porpoises, and Dall’s porpoises. Bald eagles and great blue herons are common. The island is popular with kayakers exploring the north San Juan Islands.
Nearby Attractions
Roche Harbor Resort — 0.5 miles south — has dining, a marina, and the Westcott Bay Sculpture Park. San Juan Island — the larger island — has Friday Harbor, Lime Kiln Point State Park, and the San Juan Island NHP. Stuart Island Marine State Park is 3 miles northwest.
Nearby state parks: If you have extra time, Posey Island Marine State Park is a short drive away, and Stuart Island Marine State Park is a short drive away.
Park Location
Plan your gear for Posey Island SMP
From our editorial guides, matched to this park’s activities:
Top Tours & Activities Near San Juan Islands
from $680
from $29
from $260