There are nine major Azorean islands and an islet cluster, in three main groups. These are Flores and Corvo, to the west; Graciosa, Terceira, São Jorge, Pico, and Faial in the centre; and São Miguel, Santa Maria, and the Formigas Reef to the east. They extend for more than and lie in a northwest–southeast direction. All of the islands have volcanic origins, although some, such as Santa Maria, have had no recorded activity since the islands were settled several centuries ago. Mount Pico, on the island of Pico, is the highest point in Portugal, at . If measured from their base at the bottom of the ocean to their peaks, which thrust high above the surface of the Atlantic, the Azores are among the tallest mountains on the planet.