Henderson Island is an ice-covered island 9 miles (14 km) long and rising to 240 m (787 ft), lying 9 miles (14 km) southeast of Masson Island within the Shackleton Ice Shelf. Henderson Island is located at (66°22′S97°10′E). Henderson Island was discovered in August 1912 by the Western Base Party of the Australian Antarctic Expedition under Sir Douglas Mawson and named by him for Prof. G. C.