Santo Antão (Portuguese for “Saint Anthony”), or Sontonton in Cape Verdean Creole, is the westernmost and largest of the Barlavento islands of Cape Verde. The nearest main island is São Vicente to the southeast, separated by a channel named Canal de São Vicente. It is the westernmost large island in Cape Verde and the continent of Africa, and the second largest in Cape Verde.
The island is entirely made up of volcanic material. The tallest mountain is Topo de Coroa, reaching a height of 1,979 m. The second tallest is Pico da Cruz at 1,585 m. The island is divided into north and south by a mountain range long considered impenetrable but now are crossed by two paved roads, one with mountain curves, another one opened in 2009 runs in the easternmost predominantly next to the sea. The island’s main town is Ponta do Sol on the north coast, home to the closed Agostinho Neto Airport, while its ferry port is Porto Novo on the south coast. A part of the island in the southeast has an arid climate, while the northwest receives relatively normal precipitation. Its valleys are suffering heavy erosion.
Canal de São Vicente lies to the southeast of Porto Novo and separates with the island of São Vicente.
Bathing beaches and fishing areas are found in near Tarrafal de Monte Trigo. During the rainy season, some creek beds across the island are temporarily filled with water