You might think space is the final frontier, but there's an entire alien world beneath the sea. Exploring the deepest abysses even looks a lot like exploring outer space. So, we set up some time with Fabien Cousteau, aquanaut, Jacques Cousteau's grandson, and arguably the ocean's biggest fan, to chat about what it's like. Cousteau organised a 31-day mission underwater to the Aquarius lab back in 2014.