The Navy Is Sick of the One-Person Subs It Uses for Deep-Sea Diving

Moving around underwater in a diving suit is a lot less fun than it sounds. To survive at the deepest depths, divers need enormous, cumbersome, pressure-resistant suits that limit their mobility. But the Navy is sick of trading survivability for flexibility, no matter how far into the briny deep its divers wade.

In the Navy's most recent round of technology solicitations to small businesses, the seafaring service is looking for someone to develop a lightweight atmospheric diving suit that weighs under 400 pounds and can withstand pressure at 1,000 feet below sea level. If the weight requirement still sounds pretty heavy, consider that the current generation of deep-sea suits can weigh thousands of pounds, limiting what divers can do in them.

According to the solicitation, the new diving suit is for 'expeditionary diving and salvage forces' (.pdf) and retrieving 'high value material' in 'austere environments.' Unlike the bulky suits divers currently wear ' really more like one-person submarines ' these might be light enough so divers can propel themselves with their own feet. (Current models use thrusters, not divers' legs.) Still, a wetsuit this ain't: It's still a self-contained pressure suit.

It's also extremely dangerous to dive below a few hundred feet without one of these single-serving subs. Below 500 feet, a neurological disorder called high-pressure nervous syndrome can kick in, which can lead to drowsiness and tremors. Breathing nitrogen and oxygen at depths below 300 feet can also cause blackouts and even death. Saturation diving, which relies on gradually acclimating to underwater pressure over time, isn't perfect either. Surfacing too quickly can result in the bends, a form of decompression sickness caused by nitrogen bubbles expanding and becoming stuck in vital organs.

To prevent death from happening at these extreme depths, bulky atmospheric suits maintain a steady internal pressure of one standard atmosphere, or one atm ' the same as the mean pressure at sea level. That also means deep-sea divers don't have to depressurize when surfacing. But the Navy notes: 'This size and cumbersome configuration severely constrains its use.'

Some experimental suits have some of the functionality the Navy wants. Canadian firm Nuytco Research recently developed an atmospheric diving suit called the Exosuit ADS, which can descend to 1,000 feet ' its crush depth is double that ' and weighs between 500 to 600 pounds, just over the Navy's requirement. Divers can wear flipper boots in addition to the suit's thrusters. And the Nuytco model uses a foam coating of teeny, tiny microbubbles to keep divers' limbs buoyant. The suit also has artificial hands controlled by handles contained inside.

Nor is the Navy is the only part of the military giving divers a boost. The Pentagon's blue-sky research agency Darpa wants to develop a sensor system that can detect signs of decompression sickness in divers, and adjust for it by squirting small amounts of nitric oxide into divers' lungs when there's danger. But those divers won't be operating at extreme depths. For that, you'll still need a clunky suit ' though a lighter one. With flipper boots.