The U.S. Navy's 11th Virginia-class attack submarine has successfully completed its alpha sea trials, shipbuilder General Dynamics Electric Boat reports.

The trials, directed by the U.S. Navy, involved testing of propulsion-plant operations, the submerging of the vessel for the first time, and high-speed runs on and below the surface.

"The crew and shipbuilders worked together as one unit to take this submarine to sea and put it through its paces," said Electric Boat President Jeffrey Geiger. "It was an outstanding effort by everyone involved, and demonstrates the commitment of the Navy and industry team to sustain the success of the Virginia-class submarine program."

Virginia-class submarines are fast attack nuclear-powered vessels with a top speed of more than 35 knots and a test depth of more than 800 feet. They are armed with Tomahawk cruise missiles as well as torpedoes.

Electric Boat and its construction teammate, Newport News Shipbuilding, have so far delivered 10 of the submarines to the Navy and eight more are in various stages of construction. The Navy last May ordered 10 additional submarines at a cost of $17.6 billion.