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