The Ross Ice Shelf is the largest ice shelf of Antarctica (an area of roughly 487 000 km² and about 800 km across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than 600 km long, and between 15 and 50 metres high above the water surface. Ninety percent of the floating ice, however, is below the water surface.

Most of Ross Ice Shelf is located within the Ross Dependency claimed by New Zealand.

The ice shelf was named after Captain Sir James Clark Ross, who discovered it on 28 January 1841. It was originally named the Victoria barrier by Ross after Queen Victoria and later the Great Ice Barrier, as it prevented sailing further south. Ross mapped the ice front eastward to 160°W.

On January 5, 1841, a British Admiralty team in the Erebus and the Terror, three-masted ships with specially strengthened wooden hulls, was going through the pack ice of the Pacific near Antarctica in an attempt to determine the position of the South Magnetic Pole. Four days later, they found their way into open water and were hoping that they would have a clear passage to their destination. But on 11 January, the men were faced with an enormous mass of ice.