Antarctica

It has been only 100 years since humans first occupied the continent of Antarctica (1899), and a mere 180 years since seafarers first saw the islands of the Antarctic Peninsula (1819). Yet even before they laid eyes on it, most early explorers were convinced a large, southern continent existed. They called it Terra Australis Incognita--the Unknown Southern Land.

The idea went back to the ancient Greeks, who had a fondness for symmetry and balance. There must be a great continent to the south, they postulated, to balance the great land masses in the northern hemisphere. Two thousand years later, the great age of exploration brought Europeans far enough south to test the hypothesis.

In 1520, after he had sailed through the Strait that now bears his name, Magellan speculated that the land to his south, Tierra del Fuego, might mark the northern edge of a great continent. Fifty-eight years later, in 1578, Sir Francis Drake sailed his Golden Hind through Magellan's Strait. He encountered severe weather on the Pacific side and was blown to the south of Tierra del Fuego, then east around Cape Horn. It became obvious that Magellan's "continent" was merely a series of islands at the tip of South America. If there was indeed a southern continent, it had to be further south.

It seems ironic that the severe weather that makes the southern ocean so dangerous, particularly in the south Atlantic, was a key factor in the discovery of Antarctica. Time and time again, sailors blown off course by a storm discovered new land. Often, this new land was further south than any previously known. While attempting to navigate around Cape Horn in 1619, the Spaniards Bartoleme and Gonzalo Garcia de Nodal were blown off course, only to discover the tiny islands they named Islas Diego Ramirez. This would be the most southerly recorded land for another 156 years.

In 1622, the Dutch pilot Dirck Gerritsz reported being driven south to 64°S, where he supposedly discovered a land with snow-covered mountains, a land similar in appearance to Norway. The accuracy of his latitude calculation is suspect, but it is possible that he sighted the South Shetland Islands. In 1675, the British merchant Anthony de la Roch was blown far to the east and south of the Straits of Magellan, to a latitude of 55°S, where he found shelter in an unnamed bay. During his stay at what was almost certainly South Georgia Island, he also sighted what he thought to be the southern continent to the south and east. In fact, what he saw was most probably the Clerke Rocks, which lie 48 kilometers southeast of South Georgia. Their location corresponds to where the shore of Terra Australis Incognita was placed on the Dutch East India Company map of the time, which de la Roche had studied.

Source: http://www.antarcticaonline.com/history/history.htm