Eureka, California Adventures Mountain bike through Prairie Creek State Park Coastal redwoods are the tallest living things on earth, and they can be seen in Prairie Creek State Park, one of the few remaining old growth forests. A mountain bike adventure is the best way to explore these fascinating trees; the trails are not that difficult and the scenery is fantastic. In addition to the redwoods, which are impossible to miss, watch out for wild elk and picturesque waterfalls.