Jules Dumont d'Urville discovers Adélie Land in Antarctica on January 21, 1840, claiming it for France.

The first days of the voyage from Hobart, Tasmania, had mainly involved the crossing of twenty degrees and a westerly current; on board there had been further misfortunes, including the loss of a man.

Crossing the 50°S parallel, they experienced unexpected falls in the air and water temperatures.

After completing the crossing of the Antarctic Convergence, on January 16, at 60°S they had sighted the first iceberg and two days later the ships found themselves in the middle of a mass of ice.

On January 20. the expedition had crossed the Antarctic Circle, with celebrations similar to crossing of the Equator ceremonies, and they sighted land the same afternoon.

The two ships slowly sailed to the West, skirting walls of ice, and on January 22, just before nine in the evening, some members of the crew disembarked on the north-westernmost and highest islet of the rocky group of Dumoulin Islands, at five hundred to six hundred meters from the icy coast of the Astrolabe Glacier Tongue of the time, today about four kilometers north from the glacier extremity near Cape Geodesie, and hoisted the French tricolour.

Dumont names the archipelago Pointe Géologie and the land beyond, Terre Adélie, for his wife.

The map of the coast drawn under sail by the hydrographer Clément Adrien Vincendon-Dumoulin is remarkably accurate given the means of the time.

Charles Wilkes's United States Exploring Expedition sights what becomes known as Wilkes Land in the southeast quadrant of Antarctica on January 25, 1840, claiming it for the United States, and providing evidence that Antarctica is a complete continent.

The Exploring Expedition, commonly known as the "Wilkes Expedition," includes naturalists, botanists, a mineralogist, taxidermists, artists and a philologist, and it is carried by USS Vincennes (780 tons) and USS Peacock (650 tons), the brig USS Porpoise (230 tons), the store-ship USS Relief, and two schooners, USS Sea Gull (110 tons) and USS Flying Fish (96 tons).

Departing from Hampton Roads on August 18, 1838, the expedition has stopped at the Madeira Islands and Rio de Janeiro; visited Tierra del Fuego, Chile, Peru, the Tuamotu Archipelago, Samoa, and New South Wales; from Sydney, Australia, sailed into the Antarctic Ocean in December 1839 and reports the discovery "of an Antarctic continent west of the Balleny Islands" of which it sights the coast on January 25, 1840.