Doug Allan

As soon as he dives with his head down and his feet up, he can barely draw a breath.

Gagné makes some adjustments to the design, and six months later, in June 1943, Cousteau enters the Mediterranean to test the modified apparatus.

It is a resounding success.

He is able to spend around half an hour breathing freely as he explores underwater.

His dream of becoming a man-fish has come true.

Cousteau sends word back to Gagné in Paris to apply for a patent and asks for two similar prototypes for Tellier and Dumas.

The pair called their invention the Aqualung.

It is a device that will open up the underwater world to ordinary people.

Soon Cousteau and his friends begin to clock up hundreds of dives between them.

Simone becomes the world's first female scuba diver, and even the children have the opportunity to try out their father's new equipment in shallow waters.

The sea musketeers begin exploring local shipwrecks and bring treasures back to the surface.

Crockery, silverware, even bottles of pre-war perfume.

But there are hazards in this new world too, with injuries sustained from razor-edged clams and scorpionfish.

Thrilled with their new discoveries, they experiment with how deep they can go.

Duma eventually clocks in at 210 feet.

This record-breaking depth introduces them to the so-called Rapture of the Deep, a strange euphoria brought on by inhaling nitrogen under pressure, now known as nitrogen narcosis.

Their adventures are recorded in a film titled Epave, or Shipwrecks.

When it is shown to a room full of admirals in Toulon, they immediately recognize the military potential of the Aqualung and place an order for ten of them.

In May 1945, the war in Europe finally comes to an end.

But the celebrations don't last long for Cousteau, because shortly afterwards he receives news that his brother, Pack, has been arrested as a Nazi collaborator.