The Deep

Alex Rogers has spent the past 30 years studying marine life, and is a consultant on the BBC series Blue Planet. Here, he shares his discoveries - underwater mountains, coral reefs and strange creatures - and explains the workings of this complex ecosystem, which contains 90 percent of the Earths life-forms. He goes on to warn of the threat it faces from overfishing, pollution and climate change, and suggests ways in which we can protect it.