The Ross Ice Shelf is the largest extant ice shelf in the world, forming the most southerly region of the Ross Sea and fed by the vast glaciers of Antarctica.

First known as The Great Ice Barrier, it was discovered by James Clark Ross in 1841 when he journeyed further South than Captain Cook had in the previous century. Ross's ships were Erebus and Terror, for which Ross named the two volcanic mountains he saw in the distance but could not reach due to ice.

Ross was unable to determine the extent of the Barrier. The coastal boundaries were first defined by Scott in Discovery in early 1902. These are from Ross Island at approximately 170°E to King Edward VII Land at approximately 160°W making a rough arc of 30° at 78°S.

This expedition also determined that the barrier was, in fact, an ice shelf floating on the sea but was unable to exactly define how far towards the pole it extended, though it was clear to them that it was huge.