Humboldt Redwoods State Park offers some wonderful opportunities for running among the giant redwoods. Nearly one-third of this 52,000-acre park is old-growth redwood forest—the largest expanse of ancient redwoods left on the planet. This is a huge park with many running opportunities.There are also many miles of paved roads, which are scenic and suitable for running. Mattole Rd. is a scenic road for running, as is the 32-mile Avenue of the Giants, though we note the latter is a famous ‘scenic drive’ and can feature a lot of traffic. (Note: most of the roads don’t have a shoulder, but they are listed as suitable for cycling though caution should be used!) .

There are 100 miles of trails, with trail running options for all abilities!  This page lists several trail options, ranging from easy to strenuous. 

Notes: In summer, there are some temporary bridges put in to provide access to certain parts of the park. Also, this area receives 60-80 inches of rain a year, most of it from October-April.