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Jacques Cousteau and Emile Gagnan, 1943




Jacques Cousteau is known to us as the explorer of the inner world of the ocean; he was an avid scientist, researcher, and photographer seeking to enable man’s endurance immersed in the depths of the sea. Along with French engineer Emile Gagnan, he invented the first aqualung in 1943. Although other devices were available at the time for underwater breathing -- notably that of Captain Yves Le Prieur of an open-circuit compressed-air device in 1925-- the aqualung enabled the diver to stay submerged for much longer periods of time.

The aqualung was an open circuit breathing apparatus; a simple system of gas exchange that released exhaled oxygen into the water. Weighing about 50 lbs, the original aqualung consisted of three cylinders carried on the back of the diver. The air in the cylinders, compressed to 150psi at sea level, passed through a demand regulator, which lowered the pressure of the compressed air to that of the surrounding water and provided a discontinuous flow of oxygen controlled by the inhalation of the diver. The regulator joined to a mouthpiece via two flexible tubes. As the diver exhaled, foul air escaped freely into the water through a one-way exhaust valve. The aqualung thus allowed for agile maneuvering underwater and complete immersion, along with deeper descents and longer dive times, ultimately allowing for greater exploration of the ocean environment.

The origins of the aqualung can be traced to Gagnan’s demand regulator during WWII, which would feed cooking gas to a car’s carburetor in the exact amount the engine needed. Gagnan’s regulator was then adapted for diving, and the Cousteau-Gagnan aqualung was patented in 1943. The inclusion of the demand regulator in the aqualung allowed for the flow of air from the cylinders to be provided on demand by the diver, and dive times increased to about an hour, depending on depth. However, as the dives became the deeper, not only did the dive times decrease, divers also began to suffer from the consequences of improper decompression due to nitrogen build up in their bloodstream (Cousteau, The Ocean World, 256-267).

The aqualung technology was not an isolated invention. Tailliez, a diving partner of Cousteau, once exclaimed, “each yard of depth we claimed in the sea would open to mankind 300,000km of living space” (cousteau.org). This begins to explain Cousteau’s position that the aqualung is one step towards humans’ ability to live underwater. Beyond the aqualung, Cousteau envisioned an amphibious man who could operate underwater indefinitely without breathing (Cousteau, The Ocean World). The amphibious man would have his lungs filled with a super-oxygenated liquid instead of air, circulated outside the body and through an external re-oxygenating unit attached to the human; this would allow divers to reach estimated depths of 9,000 feet without heavy diving gear. “Someday you may have 50 feet of water over New York City if the icecaps melt,” Cousteau once said. The aqualung is a step towards man’s ability to live under the ocean surface.


KEYWORDS: Demand Regulator, One-way Exhaust Valve, Amphibious Man


EXPERIMENTAL CASUALTIES: While the Aqualung was a success, many deaths occurred while experimenting undersea breathing technology due to a variety of reasons, from the Bends to embolisms. The Aqualung is still used in modern diving technology today in improved models.

CONDENSED DIVE TIME: Deeper dives significantly decreased the dive times, at the surface, dive times could last 3 hours while at a depth of 100 feet, the dive time falls to 50 minutes with most of that time being devoted to decompression during the ascent.

Auguste Piccard, 1931