Short answers, pulled from the story.
The first recorded instance of human-powered submersion was demonstrated by two Greek inventors in 1538 before Emperor Charles V in Toledo, Spain. This early vessel was described in a 1562 report by Joann Taisnier as a hollow cauldron held by ropes with seats inside for divers.
The first verified submarine capable of independent underwater operation was the Turtle, built in 1775 by American David Bushnell. This acorn-shaped device was hand-powered and used screws for propulsion to accommodate a single person.
The Confederate submarine Hunley became the first military submersible to sink an enemy vessel, the USS Housatonic, in 1864. The Hunley's explosion may have killed its crew instantly, preventing them from pumping the bilge or propelling the submarine.
The Plongeur, launched in 1863 by France, was the first submarine to successfully dive, cruise underwater, and resurface under crew control. It used compressed air for propulsion, marking the beginning of mechanically powered submarines.
The bathyscaphe Trieste reached the ocean floor in the Challenger Deep on the 23rd of January 1960, carrying Jacques Piccard and Lieutenant Don Walsh. This was the first time a vessel, crewed or uncrewed, had reached the deepest point in the Earth's oceans.
The British submarine HMS Conqueror sank the Argentine cruiser ARA General Belgrano in 1982 during the Falklands War. This event marked the first sinking by a nuclear-powered submarine in war.