Grutas de São Vicente
Just outside the village of São Vicente, you'll find a series of underground caves formed during Madeira's last volcanic eruption around 890,000 years ago. Half-hour tours led by enthusiastic guides descend about 1 km (½ mile) into the chocolate-colored rock caverns. Next door, the Centro do Vulcanismo is a slightly dated but still interesting interactive exhibition detailing the region's volcanic past, complete with a 3-D film that transports you to the center of the earth. Note that the caves are currently closed for maintenance and scheduled to reopen in 2023, so check before you visit. Dress appropriately: it's slippery underfoot and you'll often get dripped on from above.
