The story of Kursk focuses on the sinking of the Russian nuclear submarine Kursk in 2000. The Kursk was undergoing combat training when a torpedo exploded inside the submarine, killing all 118 crew members. The incident also became the worst submarine accident in history. The Russian Kursk nuclear submarine was one of the most advanced and largest tactical nuclear submarines in the world at the time, specially designed to attack aircraft carriers, and was once hailed by the media as the "aircraft carrier terminator." Like the Titanic supertanker, the Kursk nuclear submarine was once considered an "unsinkable" submarine.