Gerlache Island is the largest of the Rosenthal Islands lying off Gerlache Point on the west coast of Anvers Island, in the Palmer Archipelago of Antarctica. It was first roughly charted and named "Pointe de Gerlache" by the French Antarctic Expedition, 1903–05, under Jean-Baptiste Charcot, for Lieutenant Adrien de Gerlache. As a result of surveys by the Falkland Islands Dependencies Survey in 1956–58, this island is considered to be the feature named by Charcot; there is no prominent point in this vicinity which would be visible from seaward.
A small (41 ha) islet lying about 4.5 km to the south of Gerlache, and 500 m off the west coast of Anvers, has been identified as an Important Bird Area (IBA) by BirdLife International because it supports a breeding colony of gentoo penguins, with about 3000 pairs recorded there in 1987. It lies within ASMA 7 - Southwest Anvers Island and Palmer Basin.
This article incorporates public domain material from the United States Geological Survey document "Gerlache Island" (content from the Geographic Names Information System).