Scholars believe the resemblance of the coastline to the actual coast of Antarctica to be tenuous. For centuries before the actual discovery of Antarctica, cartographers had been depicting a massive southern landmass on global maps based on the theoretical assumption by Europeans that one must exist, if only to balance the landmass of the North. The landmass in question on the Piri Reis map would thus be simply a continuation of this tradition, with its debatable resemblance to the actual coastline being coincidental. It was widely believed that South America and, once its northern coastline was discovered, Australia, must be joined to this land mass, which was thought to be very much bigger than the real Antarctica. This theoretical southern continent, the Great Southern Land or Terra Australis Incognita (literally Unknown Southern Land), in various configurations, was usually shown on maps until the eighteenth century.
An alternate view is that the "Antarctic" coast is simply the eastern coastline of South America skewed to align east-west due to the inaccurate measurement of longtitude or to fit it on the page 1. Close examination of the coastline supports this view, revealing depictions of the basins at the mouth of the Strait of Magellan and the Falkland Islands. 2 The annotations on the map itself, stating that this region is hot and inhabited by large snakes do not fit with the likely climate and fauna in Antarctica in the 1500s. Similarly the map states that "spring comes early" to the islands off the coast, which is true of the Falkland Islands but not of any islands close to the Antarctic mainland.
Hapgood suggests that the Antarctic section of the map was copied at an incorrect scale to the rest of the map and resulted in the distortion and enlargement of the continent on several ancient maps. This would explain why there is no waterway between South America and Antarctica. He suggests several points of continuity between the Piri Reis Map and modern maps of the continent below the ice caps.
Since the Antarctic continent was not officially sighted until 1820 and its full coastline was not known until much later, this claim, if true, requires major revisions to the history of exploration.