Robert Louis Stevenson State Park, State park with hiking trails and mountain summit in Napa County, United States.

Robert Louis Stevenson State Park spans a large area across multiple counties, with forested sections, open brush-covered slopes, and Mount Saint Helena as its highest point. Trails wind through changing terrain and lead to the summit where views extend far across the region.

In 1880 Robert Louis Stevenson and his wife Fanny Vandegrift Osbourne spent their honeymoon in a cabin at a played-out mine on Mount Saint Helena, together with Fanny's son Lloyd Osbourne. Nothing of the cabin remains, but the site is marked along the summit trail. Stevenson later wrote about the stay in The Silverado Squatters. The park is California Historical Landmark #710.

The park takes its name from Robert Louis Stevenson, who in 1880 spent his honeymoon with Fanny Vandegrift Osbourne and her son Lloyd in a cabin at a played-out mine on Mount Saint Helena. Nothing remains of the cabin, but the site is marked along the summit trail. Stevenson later wrote about the stay in The Silverado Squatters.

The park entrance is off State Route 29 between Calistoga and Middletown. The hike from the trailhead to the Mount Saint Helena summit covers 5 miles (8 km) one way, so plan for a long day and carry water; the terrain is rough, with evergreen forest in the north-facing canyons and chaparral on the south-facing slopes.

On clear days, the summit reveals distant views extending far across the landscape to other mountain peaks in the region. These rare panoramic moments reward the effort of climbing and offer perspective on the scale of the surrounding wilderness.