On the way to the active volcano Piton de la Fournaise you'll pass a viewpoint at the road called Nez de Boeuf. From this spot one has a fantastic view of the valley of the river Riviere des Remparts all the way to the ocean. No hiking is necessary since the lookout is just a couple of steps from the parking lot. However, if you feel like hiking there is a short trail to the top of Nez de Boeuf.