Half Moon Island lies in the entrance to Moon Bay, between Livingston and Greenwich Islands. The 2 km (1.2 mi) long island is crescent-shaped and home to approximately 3300 breeding pairs of Chinstrap penguins. Antarctic terns, Skuas, Kelp gulls, Wilson’s storm petrels and Blue-eyed shags also breed at this site. Fur seals are often present on the beaches, along with the occasional presence of Weddell and Elephant seals. The Argentine Cámara Station is located on the southwest side of the island.

On a clear day, the peaks of the Tangra Mountains on Livingston Island form a spectacular backdrop to Half Moon Island in Moon Bay. Tangra is the supreme, mythical god in Bulgaria and many of the mountains here are named after features of that country or famous nationals as it was Bulgarians who mapped much of the area in detail in the early 2000's. The rocky areas in the foreground are all on Half Moon Island. Some of the names are explained in the key below, yellow numbers referring to features on Livingston Island, red ones to those on Half Moon Island.

Half Moon Island lies in the entrance to Moon Bay, between Livingston and Greenwich Islands. The 2 km (1.2mi) long island is crescent-shaped and home to approximately 3300 breeding pairs of Chinstrap penguins. Antarctic terns, Skuas, Kelp gulls, Wilson's storm petrels and Blue-eyed shags also breed at this site. Fur seals are often present on the beaches, along with the occasional presence of Weddell and Elephant.