Why?? In this day, a 50W solar panel can run a low pressure, depth compensated air compressor. Without the Drag on the leg and groin areas.... (or is that the appeal??)

Of course something like this shouldn't be used for any significant depth... Without proper training and "Certification" - as it is a recipe for "the Bends" for unfamiliar swimmers....
Oerhaps if batteries get close to their theoretical limitsof about 15 times the energy desnsity of LiON we can make portable Gills that mimic fish lungs and make them last a few hours below the surface.
Usually, if you want to observe fish, you will want to stay still. This wouldn't work too well for that.
Let me get this straight - if you stop swimming the system stops pumping air to you?

So if you were in a situation where you had your foot trapped by a giant clam, or trapped by a rock (a scenario beloved by many underwater movies!) not only would you be trapped under water but you would be held immobile, so the air would stop pumping and you would quickly suffocate or drown.
Yep that sounds like a workable system to me - not!!!
This has the smell of other underwater swimming systems that were so enthusiastically publicised by unskeptical arts graduate journalists...which turned out to be scams. The as started in the open water - but then cut to a pool. It talks of "philosophy". It says it's simple (but never explains the technology). Sorry I'm calling BS. This will turn out to be a scam.
James Gay
Sure fire way to drown yourself or get the bends. Getting Scuba certified ain't that hard guys. Or expensive. Trying to create some cheaper way to do something so inherently dangerous is a terrible idea.
Good lord the comments here are ridiculous. You aren't going to get the bends as the hose limits you to less than 16 feet, which means unless you're pulling the absolute length of the hose you're going to be at between 10-14 feet depth the entire time? Use your heads people. Getting a leg caught in a rock or a giant clam? First of all, it would not hinder you from moving your legs to get air. In fact that scenario actually makes the product even more compelling since you effectively have air as long as you can move your legs, unlike the snorkl or air buddy where you have a timer counting down how much air you have access to. Also, that scenario, if you dared to even bother looking up, is so absurdly uncommon, it's like questioning going hiking because of the risk of being attacked by a bear, or walking in public because of rapists. Also, observing fish doesn't require you to stay still at all? Has any of these commenters ever dived before? Fish swim away if you get too close too quickly, not simply because you're moving.
I personally love this idea for the portability and not being beheld to batteries. Whether or not it works, well, I'll wait to read the reviews, but if it works for ocean style swimming depths up to about 20 feet (something I do regularly) then I'm all in on this thing.
"Without proper training and "Certification" - as it is a recipe for "the Bends" for unfamiliar swimmers...." There is no danger of getting the bends in depths less than 25 feet so. You can stay down all day breathing compressed air at that depth without any worries.

The issue I see is that with greater depth, the air has to be compressed more, and that additional work comes from the diver. At some point, you are expending more energy compressing the air than you are swimming. As your rate of respiration goes up due to exertion, you have to swim faster to pump more air. Good recipe for drowning if you're not careful!
Bruce H. Anderson
Pressure increases with depth, so limiting depth via the tube/float will certainly help keep the pumping effort reasonable. I would guess that the diaphragm could also be activated using your arms in case a giant clam gets you. And if the diaphragm breaks/leaks, you are not that far from the surface. A Styrofoam (or blown poly) upper float instead of an inflatable one might be nice to make that piece fail-safe.
It is not the bends you need to worry about it is the over compression of the lungs.
Breathing compressed air at 16’ is 1.5 atmospheres, therefore take a deep breath, hold it, go to the surface and burst your lungs. This is why everyone except skindivers needs training when using compressed air underwater.