The Biafo Glacier is a 63 km long glacier in the Karakoram Mountains of the Northern Areas , Pakistan which meets the 49 km long Hispar Glacier at an altitude of 5,128 m ( 16,824 feet ) at Hispar La ( Pass ) to create the world 's longest glacial system outside of the polar regions . The Biafo Glacier is a 63 km long glacier in the Karakoram Mountains of the Northern Areas , Pakistan which meets the 49 km long Hispar Glacier at an altitude of 5,128 m ( 16,824 feet ) at Hispar La ( Pass ) to create the world 's longest glacial system outside the polar regions .