"Once your veins are fully saturated in nitrogen you won't be able to go back to the surface because of the decompression sickness -- we'll have to slowly come back up over 24 hours."
For Cousteau, who grew up playing on the salt-stained deck of his grandfather's boat, the ocean is a bewitching realm -- and one he wants to share with a world which has seen more people travel into deep space than deep sea.
"Being in the water is a dream, it's part fantasy," he says. "It still holds so much magic and mystery and I can only imagine what kind of sea creatures will be coming up to us during those experiments in the dark."
"My grandfather said people protect what they love. But how can you protect what you don't understand?"