The diesel-powered vessel can explore the ocean on its own for weeks, or months at a time, with a top speed of 27 knots (about 31 mph). It can be controlled remotely, but Sea Hunter can maneuver around obstacles on its own, obeying international maritime law, much like a 132-foot-long, waterborne, version of Google’s self-driving cars.

This machine however is meant to track submarines, especially the newer, quieter diesel-powered subs—which the Russians and Chinese have recently started deploying—that are difficult to spot using traditional tracking methods. The robot ship is expected to cost the US government about $20 million, with a daily operating cost between $15,000-20,000, which, according to Reuters, is far cheaper than the average operating cost for a US military vessel.

“We’re not working on anti-submarine (technology) just because we think it’s cool,” author Peter Singer, a security expert at the New America Foundation think tank, told Reuters. “We’re working on it because we’re deeply concerned about the advancements that China and Russia are making in this space.”

Sea Hunter was christened in Portland, Oregon, and will be shipped to San Diego, California, where DARPA engineers will spend the next two years testing its autonomous abilities, according to IEEE Spectrum. While the ship is not the first robot vessel—the US government already uses remote-controlled underwater bots in a range of different activities—it’s the first one that can scour the world’s oceans on its own, thousands of miles from those monitoring it.

“You really don’t want that to be a remote-controlled vessel,” Sea Hunter‘s program manager at DARPA, Scott Littlefield, told IEEE Spectrum. “You want it to be fairly autonomous so that it can do things like obstacle avoidance on its own without being joysticked around by a person.”

In maritime lore, ships without crew are usually referred to, as DefenseOne reminds us, as “ghost ships.” They were often ships adrift at sea that the crew had abandoned, and are always creepy.

This robot ship, although it may eventually spend its days soullessly roaming the seas on the behalf of the US, is not meant to invoke fear in those worried about the increasing automation of the militaries around the world, something the UN has expressed. Any decisions on whether the ship would engage another vessel with “lethal force,” deputy defense secretary Robert Work told Reuters, would remain with humans.

“There’s no reason to be afraid of a ship like this,” Work said.

Correction: An earlier version of this post, and its headline, said that Sea Hunter was a submarine, when in fact it travels on the surface of the water.

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