Dr. Catenazzi, a zoologist on the faculty of Florida International University, writes the following about Isla Mazorca:

Mazorca, similarly to Lobos de Afuera, is a guano island under the administration of a public enterprise (Proabonos) that collects and sells the guano produced by cormorants and boobies. The lighthouse itself is maintained by the Marina [Peruvian Navy] --how frequently they visit the island I don't know. As in most guano islands, there is a guardian that keeps fishermen away from stealing guano and killing cormorants. A permit from Proabonos is necessary to visit the island. All sides of the island, which roughly looks like a dome, are pretty steep or vertical rocky walls --the island is entirely granitic. I have just checked on my map and the island is 14 km west of Punta Salinas (which is also owned by Proabonos, but is currently deserted by seabirds), the closest point on the mainland. It took me about 3h to get from Huacho to Mazorca with fishermen on a small boat. There are only a few boats fishing in the area (most leave from Huacho). The exact location is 11°23'30''S / 77°45'20'' W and the area of the island is 11.63 ha [28.7 acres]. There are resident colonies of guanay cormorants, Peruvian boobies, and Inca terns; also Humboldt penguins, pelicans, Peruvian gulls are pretty common. Seabird parasites, especially blood-sucking flies and ticks, are everywhere. These parasites are in turn prey for spiders and scorpions, that are very abundant on the island.

The picture below gives us a good idea of just how steep the island is. Notice the dwelling for the caretaker at the far left.