And that doesn’t remotely approach what the Proteus can carry. Either side of the sub can hold up to 1,600 pounds of cargo.

“You can strap different types of mines and ordnance to it,” Lindman says, 3,200 pounds’ worth. That’s way more firepower than the two Hellfire missiles that fit aboard the Predator, the iconic drone plane that serves as a muse for Lindman’s sub.

All of that is in addition to its potential spying capacity. The 6,200-pound sub can hold up to 400 pounds of gear inside it — a lot of sensors and cameras to find dangers lurking in the briny deep. Or, you can cram commandos inside.

The Proteus is designed to be a somewhat autonomous vehicle: Plug in coordinates for it and watch it go. But it also has a manned function, with enough bay space to stow up to seven Navy SEALs, should they need to be inserted. But don’t keep ‘em in long; there’s not a lot of space for them to get comfortable.

The Proteus is a step in a direction the Navy’s top officer badly wants the seafaring service to travel. Adm. Gary Roughead, the outgoing chief of naval operations, has delivered speech after speech urging engineers to build an “unmanned underwater vehicle” — a robotic sub — capable of traveling thousands of nautical miles for months on end without exposing human submariners to risk. (More on that in a subsequent post.)

Proteus can’t meet Roughead’s lofty goals. It tops out at a range of 324 nautical miles before it needs to refuel, a task that will last it 92 hours. It can’t go faster than 10 knots, and the Columbia Group anticipates it’ll most likely travel between 3 and 5 knots.

But it’s a step toward a bigger unmanned sub that’s weaponized — the current ones commandos use are about the size of a torpedo. Roughead considers weaponized UUVs to be an inevitability. Conceivably, the robot subs of the future will carry weapons like torpedos to disable mines. Or, they’ll be weapons themselves, hurtling like mechanized kamikazes at a target.

The Proteus takes the first approach. Lindman imagines it strapped with a bevy of different weapons, like the MK67 Submarine Launched Mobile Mine or the MK-54 torpedo. Or it could carry the Sea Fox, itself another robot, designed to blow up mines with a shaped charge.

Gesturing to the weapons bay, Lindman says, “I can carry other vehicles” on the Proteus — even suicidal ones like the Sea Fox.

That’s if it works. Proteus won’t go into the water until the summer, near Columbia Group’s home of Panama City, Florida. The military hasn’t invested a dime into the thing’s development. But if the sub can make it out of development doing as much as Lindman envisions, the seas will be stalked by a new robotic predator.

Photo: Spencer Ackerman