The Aqualung

With the creation of the aqualung, Jacques Cousteau enabled unprecedented ocean exploration.
From this day forward we would swim across miles of country no man had known, free and level, with our flesh feeling what the fish scales know.
–Jacques Cousteau, The Silent World, 1953
Jacques Cousteau addressed the issue of airflow in underwater breathing devices with his innovative design of the regulator valve for the diving mouthpiece.
When the mouthpiece was held between his teeth and he pressed his tongue against the valve to inhale, or breathe in, air was released from the tank. When he exhaled–moving his tongue from the valve–the air stopped flowing from the tank. Because Cousteau was only wearing a mask over his eyes and nose, his exhaled air could easily escape, forming bubbles in the surrounding water.
–Kathleen Olmstead, Jacques Cousteau, 2008
Cousteau collaborated with engineer Emile Gagnan to develop this invention, called the aqualung.

Testing the Aqualung

First Tests of the Aqualung  (Cousteau Society), 1943
The first tests of the aqualung took place in the summer of 1943. The aqualung functioned perfectly, allowing Cousteau to control his air supply and stay underwater for over thirty minutes.
I flew without wings...
–Jacques Cousteau, The Silent World, 1953
The exchange of the aqualung for old diving technology made it possible for divers to explore the ocean with fewer limitations.
The basic design he and Gagnan developed in 1943 is pretty much still used today–A few refinements, but it hasn't undergone a lot of change.
–Alex Brylske, Diver and Professor of Marine Biology and Conservation, Personal Interview, 2016