This GR covers much of the island, which is considered a Biosphere Reserve, as coastal scenery alternates with the volcanic landscapes of the interior. On the first stage the main features are the natural reserves of the Praia and Baixo islets, while further inland the route includes the Furna do Enxofre (‘sulfur cave’), a volcanic cavity 40 m high and 194 m long. The highlight of the second stage is the Caldeirinha de Pêro Botelho, a volcanic cavern about 25 m deep, and traces of ancient ruts left by ox carts. The traditional windmills are another unique feature on the Azores trails.