Leviathan was conceived by Captain Kain as the prototype of a new line of battleship. In order to avoid detection by the Federation, the Leviathan was moved to the oceanic planet of Okeanos, where it was completed within a massive rift on the ocean floor. Under false pretenses, Kain lured Captain James T. Kirk and the USS Enterprise to Okeanos, where he would use the Leviathan in an attempt to destroy the Enterprise and kill Kirk, whom Kain blamed for the death of his brother Kras, as well as the loss of his honor. (TOS novel: From the Depths)