The Thwaites Ice Tongue (74º00´S 108º30´W) is a large sheet of glacial ice and snow extending from the Antarctic mainland into the southern Amundsen Sea.

On 15 March 2002, the National Ice Center reported that an iceberg named B-22 broke off from the ice tongue. The berg measured about 46 by 35 nautical miles (85 by 65 km), with a total area of some 2,120 square statute miles (5,490 km²). As of 2003, B-22 had broken into five pieces, with B-22A still in the vicinity of the tongue, while the other pieces were much smaller and had drifted considerably west.