Crestón Island is the 157-metre rocky headland that closes the south end of the harbour. It is connected to the mainland by a short causeway and is best known as the base of the lighthouse climb. The lower slopes are covered in dry scrub, cactus, and a colony of squirrels that the path up to the lighthouse passes through.
You can walk the perimeter at sea level in about thirty minutes, though most visitors just take the climb up to the Faro. The rocky shore around the base is a useful spot to see brown boobies, frigatebirds, and the occasional sea lion lifted up by the swell.