around including for Nautilus and to complete a submerged lap around the Earth. Until Nautilus commander, William Anderson, suggested the submerged trip under the North Pole, it had not even been considered. Nautilus departed from Groton on 19 August 1957 for the first attempt at sailing under the Pole, but was unsuccessful because of the ice being too deep. Another attempt was not made until the next summer. On 23 July 1958, Nautilus left the Pearl Harbor naval base heading north towards the Bering Strait. The submarine and crew crossed under the pole at 2315 on August 3 and continued for four more days until exiting from under the polar ice northeast of Greenland where Commander Anderson radioed to the President the message, "Nautilus 90 North". Even the second attempt did not go without issues, the crew having to deal with large amounts of ice blockage as well as mechanical failures aboard the sub. The hope was that the mission was timed to where the ice levels in the Arctic would be at their lowest making it easier to navigate through the waters under the pole without hitting the bottom or the top with the periscope. The expedition was also used as a testing ground not only for the sub, but as an opportunity for the Navy to experiment with different types of navigational equipment. An example of such research related to navigation by compass. Normally a ship or small craft relies on a magnetic compass which works by comparing your position to magnetic north. One major flaw with magnetic compasses is that magnetic north is not exactly on the North Pole but south of it so the crew was experimenting with a new design of the gyro-compass. As they inched farther north, the gyro-compass was much more reliable than the magnetic which pointed in nearly the opposite direction. References Scientific expeditions United States Navy in the 20th century