There are two different rock formations to visit while you are in Aruba - the Ayo and the Casibari. I love the Casibari formation because there are little paths that you can follow to walk up to the top. And once you get to the top it's a pretty cool view. Make sure you have a camera with you for this one It's a bit touristy, but I think it is a necessary part of sightseeing in Aruba.