The National Park Service offers some pretty awesome playgrounds for thrill-seekers. Fifty-nine of them, to be precise. So pass on the hotel gyms and their creaky treadmills when you’re out of town. Or, better yet, make your vacation plans with these feats in mind. Badass canyons will test your endurance and ocean waves or fjord swells will keep the adrenaline rushing. Here’s how you can turn these 10 national parks into your own rugged, backyard gym.