Réunion is a place of spectacular natural beauty and one of the island's most remarkable features are the three main cirques, Cilaos, Mafate and Salazie. A cirque (or caldera) is a natural amphitheatre, created by a volcano collapsing in on itself. Salazie is perhaps the most striking, covered with roughly 100 waterfalls, most notably The Bride's Veil (Le Voile de la Mariée) near Hell-Bourg, as well as lush vegetation. Cilaos has long been the site of a spa resort, boasting thermal baths for the wealthy inhabitants of the area in the 1800s. It was also once a refuge for runaway slaves. Today it still known for the Irene Accot Thermal Centre; a must for weary hikers. Mafate is the most remote of the cirques and its name is derived from the Malagasy for 'lethal,' illustrating the difficulty of accessing the area. Mafate is dotted with tiny hamlets (the largest is La Nouvelle) and there are no proper roads, so the only access is on foot. The cirques provide unparalleled hiking opportunities and unspoilt wilderness, and are within a few hours of Saint-Denis.