Marguerite Bay is a vast, ice-filled bay located along the west coast of the Antarctic Peninsula, recognized as the largest bay in this region. It stretches approximately 160 miles from north to south and is bounded to the north by Adelaide Island and to the south by the Wordie Ice Shelf, George VI Sound, and Alexander Island. The eastern boundary is formed by the Fallières Coast of Graham Land on the Antarctic mainland, while the western side of the bay opens into the Southern Ocean. Discovered in 1909 by the French Antarctic Expedition led by Jean-Baptiste Charcot, Marguerite Bay was named in honor of Charcot’s wife.

The bay is notable for its dramatic glacial landscapes and complex geological history. It contains a deep bathymetric trough, 50–80 kilometers wide and extending about 370 kilometers from the mouth of George VI Sound to the continental shelf edge. The seabed features rugged bedrock, large isolated basins up to 900 meters deep, and a network of smaller, interconnected basins. The area is a key site for studying the behavior of ancient ice streams, with over 17,000 mapped glacial landforms, including mega-scale glacial lineations, drumlins, grounding-zone wedges, and extensive networks of subglacial meltwater channels. These features provide valuable insights into the retreat of the Antarctic Peninsula Ice Sheet since the last glaciation, with evidence pointing to rapid ice retreat phases and significant environmental changes over the past 14,000 years.

Marguerite Bay is also home to several islands, such as Horseshoe Island and Pourquoi Pas Island, both of which have been important sites for scientific research and exploration. The bay’s thick ice cover, persistent cold, and dramatic scenery make it a challenging destination, but also a focal point for glaciological, oceanographic, and climate studies. Its dynamic environment, shaped by the interaction of ice, ocean, and land, continues to reveal important clues about Antarctica’s past and present.