The U.S. Navy just took delivery of the largest crew-less surface ship in the world. The Sea Hunter Anti-Submarine Warfare Continuous Trail Unmanned Vessel, or ACTUV, is a 132 foot long, 140 ton drone warship perfectly suited for hunting down enemy submarines.

In recent years, the role drone aircraft have played in America’s military strategy has continued to expand as technology has improved to allow the U.S. military to leverage more of the advantages allowed by autonomous aircraft in a combat zone. Long loiter capabilities, in particular, have proven invaluable to reconnaissance and even offensive operations, but until recently, these benefits have been enjoyed primarily in the sky. The ACTUV aims to change that.

The ship is not only capable of conducting long duration operations without any crew on board whatsoever, the crew cabin needed to control the vessel from the ship is actually removable. It’s been undergoing an array of increasingly complex tests over the past year, and reports indicate that the ACTUV performed so well, DARPA (Defense Advanced Research Projects Agency) actually re-classified the vessel as a reliable platform for a variety of operations. However, one remains this ghost ship’s primary function: to stalk submarines.

“This is an inflection point,” Deputy U.S. Defense Secretary Robert Work said. “This is the first time we’ve ever had a totally robotic, trans-oceanic-capable ship.”