In terms of the United Nations Law of the Sea Convention, South Africa is in the process of claiming between 300 000 and 1.4-million square kilometres - some 25% to 115% of its current 1.2-million square kilometres of land - of underwater territory off the country's mainland and around the Prince Edward and Marion group of Antarctic islands.
http://www.southafrica.info/ess_info/sa_glance/geography/maritime-claims-200605.htm