As far as locales go, the bottom of the ocean is a particularly exasperating place to explore. Anyone or anything you send down there has to contend with the dark, with thousands of pounds of pressure on every square inch, with the inability to replenish fuel supplies without returning to the mother ship.

In recent years, unmanned undersea vehicles (UUVs) have improved the situation, eliminating the need to send a human down below, or to attach an unmanned vessel to a surface ship with a long umbilical cord. Those include Boeing's Echo Ranger and Echo Seeker underwater robots, which can spend a few days at at time below the surface, with ranges measured in the tens or hundreds of miles. That's progress, but it's not enough to emancipate the UUV from the need for a nearby surface ship with a human crew, which piles on costs.

Those UUV's are "nothing more than an extension, or an application of the surface ship," says Lance Towers, who carries the impressively potent title of director of sea and land at Phantom Works, Boeing's R&D arm. They were just one step better than leaning over the ship's railing to peer into the briny deep. "We said, we need to come up with a capability that allows us to operate an autonomous underwater vehicle that does not require a surface ship," Towers says. That was in 2011.

Boeing

Now, Boeing's showing off the product of that decision. The Echo Voyager can spend six months at a time exploring the deep sea, with a 7,500-mile range, no ship needed. Structurally, the 51-foot Voyager's not too different from its little brothers, the 32-foot Seeker and 18-foot Ranger. The big difference is the introduction of the hybrid rechargeable power system.

Like Boeing's other UUVs, the 50-ton Voyager runs on lithium-ion or silver zinc batteries that power it for a few days at a time. But instead of scooting over to a ship any time it's running low on power, the Voyager just fires up a diesel generator that recharges the batteries. (It only turns on the generator at the surface, so the exhaust can be piped into the air). The Voyager works like a Chevy Volt, if the Volt carried a thousand gallons of fuel and could drive from San Francisco to Hong Kong without hitting a gas station. (The Volt is more fuel efficient, though—battling water resistance, the Voyager goes just 7.5 miles per gallon.)

Boeing says customers could use the Voyager to inspect underwater infrastructure, take water samples, create bathymetric maps of the ocean floor, or help with oil and gas exploration. The UUV can link up with satellites to send data back to its land-dwelling bosses, and uses standard commercial interfaces, so clients don't have to adapt their equipment or software to use it. And because it will spend so much time wandering on its own, the Voyager's packed with redundant systems and backups, Towers says, which partly accounts for its size.

The Voyager, which will be capable of operating under 11,000 feet of water, has already spent time testing in Boeing's 35-foot deep pool in Huntington Beach, California, and will start sea trials off the California coast this summer. Boeing hasn't revealed its price, or when it will be commercially available. But whenever it's ready to strike out on its own, it'll make the ocean that much less of a pain in the ass to explore.