The islet of Branco (3 km2) is not far from Raso and is quite high (327 m), in relation to its small size (3,975 m long and 1,270 m wide). Seen from a distance, it resembles a fortress, rising precipitously from the sea. The terrain is mostly steep, except for a flat area on the southeast tip. On the southern and western flanks, striking bands of organogenous sands ascend halfway up the slope. The climate is hyper-arid, with scant, irregular rainfall, but in good years a very striking green carpet covers the gentler slopes from September to November.
This islet is currently uninhabited, but in the 19th century was a kind of natural prison, where inmates were left to fend for themselves; they survived on seabirds, reptiles and sea food.
Branco, along with Santa Luzia and Raso, is part of a nature reserve declared in 1990. Despite the ban on fishing because of fragile seabird colonies and natural resources, which is also true for Raso, Branco is still visited by fishermen from various islands. Fishing boats usually approach from Tarrafal, on São Nicolau, because of the rich fishing grounds in the strait that separates that island from the islets. Occasional visitors also include ornithologists, geologists and other naturalists, who come to carry out studies in situ or to observe the birdlife. These visits require adequate monitoring in order to protect the fauna, which is important for conservation and scientific purposes on both Branco and Raso.