Jacques Cousteau co-invented the aqua-lung, which brought diving to the masses, he pioneered underwater camera techniques, and he was the godfather of the modern conservation movement. But 100 years since his birth, Cousteau remains somewhat of an enigma.
Growing up, I remember Saturday mornings vividly. As soon as we heard that distinctive epic theme music trill out, my brother and I knew there was three seconds to don our red caps (pulled down at a jaunty French angle) and jump in front of the TV for the next instalment of Cousteau's underwater adventures.
Who didn't want to be a member of Jacques Cousteau's Calypso crew? The Calypso, as it set sail into the next conservation adventure, was the most exciting place to be on the planet.
So in his anniversary year, I set out to find the man behind the French accent. What drove him to his impossible challenges and, when he died in 1997, who took on the Cousteau cap?
As ocean conservation becomes one of the biggest challenges of our time, what can we learn from Cousteau to take forward in communicating the intrinsic value of the oceans today - and to help a whole new generation fall in love with the sea?
As Cousteau said: "People protect what they love. A lot of people attack the sea, I make love to it."
But Cousteau was not always a conservationist.
He was born in an era when blowing things up (including habitats and other species) for the sake of science and exploration were far more the norm.
Yet as the world became more and more connected with modern technologies and with the birth of TV, he soon began to realise the devastating effects of human impact on our planet.
Turning this new media to his advantage, Cousteau realised the red cap could be his iconic symbol and TV his powerful international communication tool.
Soon, Cousteau became the most important spokesperson for the world's health.
Motivating generations to protect the oceans, from Sylvia Earle, the famous diver, to Wes Anderson the director of the film The Life Aquatic with Steve Zissou (a film inspired by Cousteau), his work has touched many people.
But his legacy is more complicated.
Whilst his family, including his son Jean-Michael and his grandchildren, have all devoted their lives to the ocean, the mantel of the Calypso or red cap seems more illusive.
The crew members of the Calypso have carried on with Cousteau's work and I was eager to meet them and get a sense of what life was like onboard the great ship.
So on a sunny September day, I found myself standing at the Harbour Key in Marseilles with Albert Falco, former captain of the Calypso, and Denis Martin-Laval, former ship's doctor.
These were men well into their 80s whose lives on the ocean had left them far younger in every way than many half their age. (Readers take note.)
To meet them was an exhilarating experience, especially when I was invited to go back to Denis' house for lunch and to take a tour of his handmade model of the Calypso. Denis talked me through his experience on the ship, as he peeled back layer after layer of the exact replica.
You could see not only how important this boat had been to the conservation movement, but also how it has been a giant chapter in these men's lives - Albert Falco was captain for 40 years.
A feeling of excitement and camaraderie of long days at sea and a sense of purpose also overwhelmed me. I could almost smell the salt air.
Back at the quay side in Marseilles, I thought about the anticipation there must have been as the Calypso prepared to set sail on its next high seas adventure.
It was these people coming together to do great things, seemingly impossible things, that created a conservation legacy worth remembering. It was certainly this magic that we need to hold onto to encourage new conservationists into the world.
As Cousteau said: "The sea, the great unifier, is man's only hope. Now, as never before, the old phrase has a literal meaning: we are all in the same boat."
You can listen again to The Impossible Life of Jacques Cousteau from the BBC World Service here. You can also download this programme, and previous documentaries, as a podcast.