Caldeira and Furna do Enxofre Trail, Graciosa

The trail starts at the Caldeira de Santa Cruz car park, reached by car from Santa Cruz da Graciosa; there is no scheduled bus to the trailhead. No permit is required to walk the rim, but entry into Furna do Enxofre cave itself follows posted opening hours set by the site managers. The out-and-back route covers 4 km with about 150 m of cumulative elevation gain, rated easy, circling part of the rim of Graciosa's central caldera before descending to the entrance of Furna do Enxofre. The path is packed dirt with a paved and stepped section near the cave entrance; shade is limited on the open caldera rim but increases near the cave mouth, and exposure is minimal since the trail follows established paths rather than cliff edges. Landmarks include panoramic views across the caldera floor from the rim, the cave entrance itself, and, inside via a spiral stone staircase, an underground lake with sulphurous, faintly volcanic-smelling water and gas vents in the cave walls. A shorter option covers just the rim viewpoint without descending into the cave, for a walk of about 1.5 km. There are no refuge huts on the trail, and the sulphurous cave water is not for drinking, so hikers should carry their own water. Because the cave interior can have reduced air quality near the gas vents, visits are sometimes restricted, and a torch or headlamp is useful for the descent even when cave lighting is present.