The question of how much of Antarctica has been explored is complex because the answer depends entirely on what “explored” means for a continent almost entirely covered by a massive ice sheet. Exploration is a multi-layered process, extending from the visible surface down to the hidden bedrock and the systems beneath the ice. While the continent’s perimeter is well-charted, its foundation—the subglacial landscape—remains largely unknown. A significant portion of the continent’s total area, particularly the world beneath the ice, is still in the early stages of discovery.
Defining Exploration on an Ice Continent
In the Antarctic context, exploration is generally separated into three distinct tiers. The most basic level is surface mapping, which involves visually charting coastlines, mountain ranges, and the ice sheet’s topography. This process establishes geographic boundaries and features that are accessible to human observation and travel.
The second tier involves detailed geological surveying, requiring scientists to physically access small, exposed areas of rock or collect samples to understand the continent’s composition and history. The deepest, and least explored, tier is the mapping of the subglacial topography and hydrology, which constitutes the bedrock landscape and the liquid water systems beneath the ice. Because approximately 98% of the continent is covered by ice, merely charting the visible surface is not considered full exploration.
Historical Milestones in Surface Mapping
The first phase of Antarctic exploration focused heavily on charting the coastline and establishing a human presence on the continent’s edge. Initial expeditions, beginning in the early 19th century, were dedicated to confirming the existence and extent of the landmass, replacing the long-held myth of an unknown southern land with reality. These efforts successfully delineated the continent’s perimeter and began to map the major ice shelves and peninsulas.
The early 20th century saw the push into the interior, aiming to reach the South Pole and map accessible mountain ranges like the Transantarctic Mountains. Expeditions relied on physical traversal, often using sledges and limited aerial reconnaissance to chart major geographic features. This phase of exploration addressed the accessible surface, visually mapping the topography of the ice and the small fraction of exposed rock, establishing the known surface perimeter.
The Uncharted Continent: Focus on Subglacial Systems
The vast majority of Antarctica, covering roughly 14 million square kilometers, is capped by the Antarctic Ice Sheet, which holds over 90% of the world’s freshwater. Because the ice cover is so extensive, the actual landmass beneath—the bedrock—is the largest unexplored land surface on Earth. The thickness of the ice, which can reach nearly five kilometers in places, means that much of the underlying geology remains unknown.
Beneath this massive ice layer exists an extensive and dynamic network of subglacial water systems, including rivers and lakes. Scientists have currently identified over 400 subglacial lakes scattered across the continent. Lake Vostok, the largest of these, is buried under nearly four kilometers of ice and has been isolated from the surface environment for an estimated 15 to 20 million years. The discovery of these systems, confirmed largely through remote sensing, illustrates the scale of the hidden world that has not been physically explored or mapped in detail.
The bedrock topography, which controls the flow of the ice sheet, features rugged mountain ranges, deep canyons, and vast basins. Even the most recent and comprehensive maps of the subglacial landscape are based on interpolated data, meaning they rely on educated estimates between widely spaced measurement points. This lack of direct, continuous data means that the continent’s foundation is still largely a blank slate for geological and hydrological understanding.
Modern Technological Survey Methods
The exploration of Antarctica’s hidden world is now driven by advanced remote sensing and geophysical techniques. Airborne ice-penetrating radar is a primary tool, transmitting radio waves down through the ice to measure the depth and map the shape of the bedrock and detect liquid water beneath. Scientists fly grid patterns over the continent, slowly building up a three-dimensional map of the subglacial landscape.
Satellite altimetry is another method, using instruments like the European Space Agency’s CryoSat-2 to measure minute changes in the elevation of the ice surface. These changes, such as bulges or depressions, can indicate the filling or draining of subglacial lakes, providing evidence of an active hydrological system far below the surface. Sophisticated models and machine learning are also employed to integrate sparse data and infer the characteristics of the bedrock in vast, unsurveyed regions. This process is slow and costly, but it continues to reveal new, complex features like interconnected subglacial lake networks.