20,000 Leagues Under the Sea: Submarine Voyage the cavern entrance simulating a surface storm, the Captain would order the submarine down into the depths as a precaution, and the guests enter the show building section of the attraction. Within minutes, the devastation such natural phenomenon can create was made clear with the ominous Graveyard Of Lost Ships, with shipwrecks from various centuries littering the sea bed, guarded by the silent, gliding figures of sharks. Leaving the destruction behind, the Nautilus would reach the North Pole, circumnavigating the Polar Ice Cap from below the surface, and narrowly avoiding large icebergs stabbing through the water. Venturing deeper, the Nautilus
North Pole will be entirely free of ice in the summer. This may have significant commercial implications; see "Territorial Claims," below. The retreat of the Arctic sea ice will accelerate global warming, as less ice cover reflects less solar radiation, and may have serious climate implications by contributing to Arctic cyclone generation. Polar bears are believed to travel rarely beyond about 82° North owing to the scarcity of food, though tracks have been seen in the vicinity of the North Pole, and a 2006 expedition reported sighting a polar bear just from the Pole. The ringed seal has also been seen at