The island is a stratovolcano some 3 km long by 2.4 km wide, reaching a height of 164 m above sea level. It is approximately 123 million years old and was formed from even older oceanic crust. The south-western part is a dry, boulder-strewn plain. There is little vegetation apart from an area of grassland in the south-west. The entire coastline consists of rocky cliffs. Along with nearby Santa Luzia and Ilhéu Branco, it was declared a protected area in 1990.