Located 1.5 km (0.9 mi) southwest of Robinson Crusoe Island, it has a mainly flat surface, with a maximum altitude of 376 m (1,234 ft) at Johow Hill.

Coming from the north, the island of Santa Clara has the appearance of a cliff or escarpment; but approaching from the south, shows an eroded quirky aspect of conical mounds and strangely cut rocks.

The climate is subtropical, strongly influenced by fluctuations in the general northward flow of the cold sub-Antarctic Humboldt ocean current and the southeast trade winds, which create a high-winter and low-summer rainfall pattern and a stable temperature environment.

Santa Clara is generally desolate and barren, but on its eastern slope there are some trees, and on the northwest tip a periodical stream of water runs along the gorge, which reaches the sea.

Nearly all of Santa Clara is abundant in the introduced Rubus ulmifolius, Aristotelia chilensis, Ugni molinae, Lantana camara and Lonicera japonica.

Some have the potential to be serious pests, having fleshy fruits that are bird-dispersed, in addition to weeds such as Danthonia collina, Stipa laevissima and Piptochaetium bicolor.