The extinct volcanic cone of Mt St Helena marks a dramatic end to Napa Valley, and you can explore it at this undeveloped state park (napaoutdoors.org; free; no bathrooms, camping, trash collection or water) 8 miles north of Calistoga.
It's a strenuous 5-mile climb to the peak’s 4343ft summit, but what a view – 200 miles on a clear day. For a shorter hike with views over valley vineyards, take Table Rock Trail (2.2 miles one-way) from the parking-area trailhead. Check conditions before setting out; it often gets snow in winter. Super-fit hikers can also tackle the nearby Oat Hill Mine Trail. It's one of Northern California’s most technically challenging trails – 8.3 miles (one-way) with an elevation change of 1500ft along an 1893 stagecoach route – and draws hardcore mountain bikers and hikers.
From these heights, you can see Calistoga as 19th-century author Robert Louis Stevenson did: "Calistoga itself seems to repose on a mere film above a boiling, subterranean lake." The park also includes the old Silverado Mine site where, in 1880, Stevenson and Fanny Osbourne honeymooned – broke, sick and cold, in an abandoned bunkhouse. They miraculously survived and equally miraculously stayed married, and he became famous as the writer of Treasure Island, Silverado Squatters, and Dr Jekyll and Mr Hyde.
