São Vicente is the gateway to Madeira's most extraordinary geological attraction — the São Vicente Caves and Volcanism Centre are a labyrinth of 890,000-year-old lava tubes that end at an opening onto the ocean, one of the most singular sights on the island. The town sits at the mouth of a river flanked by some of the island's greenest and most luxuriant valleys, and the municipality includes Seixal, famous for its black-sand beach and the waterfalls that plunge straight into the Atlantic.