The Caldeira is a vast crater covered with vegetation, which encloses inside the famous Furna do Enxofre, true ex-libris of the island. The descent to this cave, which takes the visitor to the depths of a dormant volcano, is a unique experience. It is worth to appreciate the beauty of Caldeira and the panoramas that are reached from there, on the islands Terceira, S. Jorge, Pico and Faial. (Regional Natural Monument).
Source: fifecooler.com