At 3 a.m., when the crew of the Nautilus reached the South Pole, an Iceberg collapsed on top of them creating a tunnel of ice. In order to escape this tunnel, the Nautilus traveled backwards but the iceberg suddenly shifted, trapping them. Their only option was to dig their way out, so the crew proceeded to manually dig a hole in the thinnest part of the ice. After digging for a day and not succeeding, the captain has the idea to warm the water around which would melt the ice and make it easier to dig. After the ice was only a yard thick they used the Nautilus to break through the ice and then they retrieved air from the surface.