The island is long and across. It rises steeply to elevations of up to 250 m from a rocky coastline with raised pebble beaches. It has volcanic origins, with about half the land surface covered by a permanent, crevassed icecap. Ice-free areas have a sparse vegetation of mosses and lichens. The bedrock of the island is granodiorite,
A large number of locations on the island have been individually charted and named. Unless otherwise specified, the following features were first charted by the French Antarctic Expedition during their winter on the island, and named by Captain Jean-Baptiste Charcot. Rouch Point forms the northwest end of Petermann Island. It was named for Jules Rouch, the expedition's oceanographer. Godfroy Point marks the northern extremity of the island. It was named by Captain Charcot for Rene Godfroy, sub-lieutenant on the Pourquoi-Pas. Liouville Point marks the northeast end of the island. It was named for J. Liouville, the expedition's zoologist. Depeaux Point forms the south end of the island. Port Circumcision is a cove indenting the southeast side of Petermann Island. It was discovered on January 1, 1909. In the Roman Catholic calendar, this date is the Feast of the Circumcision of Christ, for which Captain Charcot named the cove. The cove served as a base for the Pourquoi-Pas during the 1909 winter season. Also on the south end of the island is Megalestris Hill, a rocky hill approximately high. It was named Megalestris after an obsolete generic name for the south polar skua, which are found on the island. A cairn with a leadplaque was erected on the hill in 1909. The original plaque has since been removed to the Museum National d’Histoire Naturelle in Paris, but the cairn, with a replica plaque, has been designated a Historic Site or Monument, following a proposal by Argentina, France and the United Kingdom to the Antarctic Treaty Consultative Meeting.
The island has been identified as an Important Bird Area by BirdLife International because it supports a breeding colony of about 3,000 pairs of gentoo penguins. Other birds nesting at the site in smaller numbers include Adélie penguins, imperial shags, Wilson's storm petrels and south polar skuas.
Groussac Refuge
Groussac Refuge is an Argentine naval refuge in Antarctica, located on the southern coast of the Port Circumcision, on Petermann Island, next to the west coast of the Antarctic Peninsula. The refuge was inaugurated on February 6, 1955 and is operated by the Argentine Navy and was occupied periodically by personnel of the British Antarctic Survey of the former Faraday Station. The refuge take place in the middle of a colony of Gentoo penguin. Its current name is in honour of Paul Groussac, a French writer and historian who lived in Argentina, author of a plea on the Argentine claim of the Malvinas Islands and biographies of Argentine national heroes.