Furnas do Cavalum (Grutas do Cavalum)

A group of four cavities in the parish of Machico, one of the few known lava-tube examples on the island. These conduits form when the surface of a flow cools fast while the inside stays liquid and drains away, leaving an empty channel. The four cavities, of different sizes and altitudes, hold a varied cave fauna, with species found only in Madeira. The name refers to a legendary figure, a horse with bat's wings.