Planning to hike in Boulder during your vacation? Heading out on the trails is easy in Boulder, where three dozen trailheads are right within the city limits. There's pretty much always a trail nearby. To help you narrow down Boulder's 150 miles of hiking trails, check out the ideas below. The Boulder Hiking Guide is a great resource, with 11 trails rated by level of difficulty. Or call our visitor center for personal recommendations: 303-442-2911.