🏆🏆🏆🏆🏆 Smallest Marine Park — Just 1 acre! — The SMALLEST state park in Washington, a tiny rock island in the San Juans with camping for just 16 people
Posey Island Marine State Park is the smallest state park in Washington — just 1 acre of rocky island in the San Juan Islands near Roche Harbor. Despite its tiny size, the island offers 2 campsites for up to 16 people — making it one of the most intimate camping experiences in the Pacific Northwest. The island is accessible only by kayak or small boat. Named for the wildflowers (posies) that bloom on the island in spring, this miniature park offers big views of the San Juan archipelago and the Olympic Mountains beyond.
Visitor Information
| Detail | Information |
|---|---|
| Location | San Juan Islands, WA |
| Entry Fee | Discover Pass required |
| Size | 1 ACRE — WA’s SMALLEST park! |
| Camping | 16 people max — most intimate! |
About Posey Island
Posey Island Marine State Park is the smallest island park in the Washington state park system — just one acre! Located in the San Juan Channel near Roche Harbor on San Juan Island, the tiny island offers a uniquely intimate camping experience. Only 16 people are allowed on the island at once, ensuring a private island experience.
Things to Do
Boat-in or kayak-in camping on your own private island (2 primitive campsites, max 16 people), kayaking, crabbing, and watching boat traffic in the San Juan Channel. It’s the ultimate “private island” experience on a state park budget.
Insider Tips
Smallest state park: Posey Island is one of Washington’s smallest state parks — just 1 acre in the San Juan Islands. Pro tip: The tiny island has one campsite — reservable in advance, it’s arguably the most exclusive camping spot in Washington. Kayak camping: The San Juan Islands offer world-class kayak camping — paddle between marine state parks on multi-day trips.
Best Time to Visit
Summer: Peak kayak camping season. Fall: Quiet paddling. Spring: Low tides reveal marine life. Winter: Not recommended for camping.
Frequently Asked Questions
Can I camp on a 1-acre island?
Yes — Posey Island’s single campsite accommodates up to 16 people. It’s boat/kayak access only — no water, no facilities beyond a composting toilet. Bring everything you need, including water. The experience of having an entire island to yourself — surrounded by orcas, eagles, and seals — is unforgettable. Reserve well in advance for summer weekends.
More parks nearby: Posey Island SMP is a short drive away, while Stuart Island Marine State Park lies a short drive away.
🏝️ Visit Posey Island Marine SP
1 acre — WA’s SMALLEST park! Camping for 16 in the San Juans!
Wildlife & Nature
Posey Island Marine State Park — a 1-acre island in the San Juan Islands near Roche Harbor — is one of the smallest state parks in Washington. The island accommodates just 2 campsites. Harbor seals rest on nearby rocks. Bald eagles soar overhead. The tiny island offers an intimate, uncrowded camping experience surrounded by the rich marine waters of the San Juan archipelago.
Nearby Attractions
Roche Harbor — 0.5 miles southeast on San Juan Island — has a resort, marina, sculpture park, and the historic Hotel de Haro (1886). English Camp (San Juan Island NHP) — 3 miles south. Friday Harbor — 10 miles south — has the Whale Museum. Stuart Island is 3 miles northwest.
🐾 Dogs & Pets at Posey Island Marine State Park
- Pets allowed? statewide rule
- Pets are allowed in most Washington state parks but must be under physical control on a leash at all times.
- Leash rule statewide rule
- 8 ft maximum leash required; pets must be under physical control
- Beaches & swim areas statewide rule
- Pets are not permitted on designated swim beaches
- Cabins & lodging statewide rule
- Pets are not allowed inside vacation houses but are permitted in designated pet-friendly cabins and yurts (e.g. Grayland Beach, Seaquest, Ike Kinswa — Cape Disappointment does NOT allow pets in its yurts), typically up to two pets, with a pet fee
- Pet fees statewide rule
- No day-use pet fee; $15 per night pet fee in pet-friendly cabins/yurts
- Statewide exceptions statewide rule
- Director-designated off-leash areas are exempt from the leash rule and are conspicuously posted
Are dogs allowed at Posey Island Marine State Park?
Pets are allowed in most Washington state parks but must be under physical control on a leash at all times. Individual parks can post stricter rules — check signage on arrival.
Rules verified July 2026 via parks.wa.gov. More: Washington state parks guide · Dog rules in all 50 states compared
Park Location
Plan your gear for Posey Island Marine State Park
From our editorial guides, matched to this park’s activities:
Top Tours & Activities Near San Juan Islands
from $680
from $29
from $260