General Dynamics [GD] Electric Boat’s attack submarine Mississippi (SSN-782) returned to its shipyard yesterday after completing its first open seas voyage, according to a company statement.

During its first open seas voyage, also known alpha sea trials, the Mississippi submerged for the first time and conducted high-speed runs on, and under, the surface to demonstrate that the submarine’s propulsion plant is fully mission-capable, according to a statement.

Mississippi is the ninth ship of the Virginia class, according to a statement.

Electric Boat and its major subcontractor, Newport News Shipbuilding, a division of Huntington Ingalls Industries [HII], have received contracts to build the first 18 submarines of a planned 30-ship Virginia class under a teaming agreement, according to a statement.