Trione-Annadel State Park

Trione-Annadel State Park is a California state park in the United States. It is situated at the northern edge of Sonoma Valley and is adjacent to Spring Lake Regional Park in Santa Rosa. It offers many recreational activities within its 5,092-acre (2,061 ha) property.

The rock formations of Trione-Annadel have played a central role in its history: its volcanic origins, the Native American use of obsidian, the early 1900s mining of cobblestones, and modern hikers' appreciation of its volcanic rock outcrops. These lands were occupied by the Wappo and Pomo people in prehistoric times, who would have primarily inhabited the riparian zones and the marsh perimeter. Annadel includes what some biologists consider the best example of undisturbed northern oak woodlands in existence.

Visitors can enjoy the park's diverse wildlife and scenery during any time of the year but are perhaps most rewarded from April through June when most wildflowers are in bloom. The 2017 Nuns fire burned the southern portion of the park.

Trione-Annadel State Park occupies a particular place in the imagination of American public lands. As a State Park in California, it represents a deliberate choice — by the people who advocated for its protection, and by the National Park Service rangers who maintain it — to keep this landscape available to anyone willing to make the trip. That accessibility is the quiet miracle of the park system.

The pages linked below break the visit down into the four practical questions every traveler asks: where can I hike, where can I sleep, what else is worth seeing while I'm in the area, and what should I know before I show up. Each one is written from the perspective of someone planning their first trip — assume nothing, explain what's worth explaining, and skip the marketing language. If you've been here before, treat these guides as a refresher and a way to discover the corners you missed last time.

What this guide covers

Over the next four pages, this field guide breaks Trione-Annadel State Park into the practical questions every traveler asks: which trails are worth the effort, where to sleep both inside and outside the park boundary, what else is worth a stop in the surrounding region, and the small-but-essential tips that make the difference between a stressful first day and a smooth one. Use the navigation above to jump between sections, or read them in order — they're written to flow.

• Hikes — short loops, half-day trails, and backcountry routes
• Camping — drive-in campgrounds, RV sites, and backcountry permits
• Nearby attractions — gateway towns and adjacent public lands
• Visitor tips — timing, fees, weather, and what to skip

Logistics at a glance

Use this quick reference when you're putting together your itinerary. The figures below are the most-asked questions every visitor needs answered before arrival, summarized in one place.

Designation	State Park
State	California
Entrance fee	Varies — check the official park site below for current rates.
Visitor center hours	Most open daily 8–9am to 4:30–6pm. Reduced winter hours common.
Best months	Plan around the weather notes above.
Camping inside park	See the camping guide for campground details, fees, and reservation windows.
Nearby gateway towns	See nearby attractions for lodging and supply stops.