Short answers, pulled from the story.
The United States Navy purchased its first commissioned submarine, the Holland VI designed by John Philip Holland, on the 11th of April 1900. The vessel had been launched on the 17th of May 1897 at Navy Lieutenant Lewis Nixon's Crescent Shipyard in Elizabeth, New Jersey.
US submarines represented only about two percent of the US Navy but destroyed over thirty percent of the Japanese Navy, including eight aircraft carriers, one battleship, and eleven cruisers. They also sank over sixty percent of Japan's merchant fleet, totaling one thousand five hundred and sixty enemy vessels and 5.3 million tons of shipping.
Germany lost about twenty-eight thousand submariners out of forty-one thousand who served in U-boats, a casualty rate of approximately seventy percent. In total, seven hundred and ninety-three U-boats were lost by the end of the war.
The deepest dive was made by Trieste on the 23rd of January 1960, reaching the ocean floor in the Challenger Deep, the deepest southern part of the Mariana Trench, carrying Jacques Piccard and Lieutenant Don Walsh of the US Navy. Onboard systems indicated a depth of 11,521 meters, later revised to 10,916 meters.
Submarines began operating under Arctic ice as early as 1930. On the 3rd of August 1958, USS Nautilus became the first vessel to reach the North Pole, using an inertial navigation system. On the 6th of May 1986, three submarines met and surfaced together at the Geographic North Pole, the first triple-submarine surfacing at that location.
The first wartime sinking by a nuclear-powered submarine occurred in 1982 during the Falklands War, when a British nuclear submarine sank the Argentine cruiser. After the sinking, the Argentine Navy concluded it had no effective defense against submarine attack and withdrew its surface fleet to port for the rest of the conflict.