At present, the submarine that can dive the deepest in the world is the Japanese submarine kaiko. Its diving position is at the bottom of Mariana Trench, the deepest trench in the world10975m.
The first nuclear submarine in the world was the Nautilus of the United States, which began its first trial on June 24th, 1954/KLOC-0, announcing the birth of a nuclear-powered submarine. There are six countries in the world that openly claim to have nuclear submarines, namely the United States, Russia, Britain, France, China and India (India's nuclear submarine destroyers are under construction). Among them, the United States and Russia have the most nuclear submarines. The emergence of nuclear submarines and the application of nuclear strategic missiles have brought the development of submarines into a new stage. Nuclear submarines equipped with nuclear strategic missiles are underwater deterrent nuclear forces.