For all its stunning city skylines, hundreds of miles of golden beaches and fun-filled theme parks and attractions, there is nothing which epitomises the great American outdoors more than its national parks, each presenting a unique landscape of incredibly diverse natural beauty, ideal for hiking, biking, riding, rafting and camping. No trip to the Western states of the US would be complete without visiting at least one of these magnificent areas and, with so many options, this is our guide to those that should be high on your agenda.