Amundsen Sea is the marginal sea off the coast of Marie Byrd Land between Cape Dart, Siple Island, on the west and Cape Flying Fish, Thurston Island, on the east. It was named by the Norwegian expedition of 1928-29, under Capt. Nils Larsen, while exploring this area in February, 1929. Amundsen Sea was named for Capt. Roald Amundsen, famous Norwegian explorer who was first to reach the South Pole. The sea has been defined with greater precision through discoveries of the U.S. Antarctic Service (1939-41), USN Operation Highjump (1946-47) and U.S. exploration in the post-IGY years.