Boulder is surrounded by thousands of acres of recreational open space, conservation easements, and nature preserves. Almost 60% (35,584 acres (144.00 km)) of open space (61,529 acres (249.00 km)) is open to the public. There is world class hiking trails throughout the city-owned and county-owned open space. The most popular trailheads are near Chautauqua Park in southwestern Boulder, while others are at the Western edge of the city or a short drive away. The trails vary in difficulty: some are quite easy while others are challenging. The City of Boulder Open Space website is a resource for information about outdoor activities and volunteer opportunities. Shorter summit hikes include Flagstaff and Mount Sanitas to the North. Mountain biking single track is also available. North Boulder is the road biker's most popular starting point. There is an abundance of rock climbing for all skill levels.
World-class rock climbing is found in nearby Eldorado Canyon (traditional protection), near the small unincorporated community of Eldorado Springs, six miles (10 km) south of Boulder. Eldorado Canyon is most famous for its hundreds of world-renowned rock climbing routes. There is also high quality climbing routes available in the city open space, including climbing routes of varying difficulty on the Flatirons themselves (traditional protection). Boulder Canyon (sport), directly west of downtown Boulder, also has many good routes. All three of these areas are affected by seasonal closures for wildlife.
Boulder is home to USA Ultimate (USAU), the governing body for the sport of Ultimate in the United States. USAU is a player-run non-profit organization, founded in 1979, with over 27,300 members and hundreds of volunteers.
Boulder is also the Headquarters of USA Rugby.
Film
Boulder International Film Festival
BIFF is held each
