George VI Ice Shelf is about 450 km long, 20–70 km wide, and averages 250 m in thickness. It is bordered by Alexander Island to the west and by the Antarctic Peninsula to the east (Fig 1). The ice shelf is fed by glaciers flowing westwards from the Palmer Land plateau. In summer (November to late February) the ice shelf undergoes considerable surface melting and meltwater lakes form over an area of 4 500 km2 between 70°15′S and 72°00′S. The lakes and pools vary in size from a few centimetres deep and several square metres in area to a few metres deep covering areas of several square kilometres (Fig 2). Most of the lakes are characteristically elongate and ribbon-like and hence are termed ‘ribbon lakes’. From mid November to late February the lakes are a major obstacle to sledge parties travelling over the ice shelf.