Historyhijacking of a Russian nuclear submarine. As it docks on top, the crew board and attack the sub's crew. Following Aquaman's intervention, it would seem that David Kane is the only user of the sub now.
Meeting with OrmSometime later, in the North Sea, David Kane sits atop the sub whilst waiting for Orm to show up. When his subordinates arrive, they attempt to give Kane his payment for accomplishing his task; but he refuses, demanding that Aquaman be brought to him (as punishment for killing Kane's father).
Birth of Black Manta
Later on, after Aquaman and Mera fled to the surface world to begin the search for Atlan's Trident, Orm gifted Kane with advanced prototype Atlantean weaponry to lead his Men of War to hunt down, and kill, both of them. Aboard the Manta-Sub, Kane retro-fit numerous pieces of tech into a fearsome, suit of armor to have an edge against Aquaman.
The submarine is equipped with a gattling gun as its primary weapon and is capable of travelling at high speeds while also remaining undetectable by sonar.