In the days of the Mayas, cenotes – deep, natural pits on the Yucatan peninsula - provided the only means of obtaining drinking water. But in the mythology of this advanced civilisation, these waterholes and caves were also the entrance to Xibalba – the underworld. All deceased were obliged to pass through Xibalba and wait there until they were called into heaven. It was a place in which one made sacrifices to the gods – objects of daily life, as well as bloody, human sacrifices. To this day, the relics of these acts are still in place preserved underwater for more than a thousand years. The entrance to the underworld begins at a dirty waterhole in the middle of the Mexican jungle overgrown and barely recognisable. But immediately after entry, a hall of breath-taking dimensions and beauty is revealed. As if they were sculptures, stalactites and stalagmites lend the underwater cave an almost sacred ambience. By now, one has succumbed to the fascination emanated by the world’s largest underwater cave system. We accompany four professional research divers to Yucatan – a team of specialists, able to squeeze their bodies through crevices and holes, barely larger than their bodies and who master dives that would push even the most experienced divers to their limits. With them, we penetrate worlds only a few people have ever ventured into. We encounter the remains of human victims, prehistoric fireplaces and primeval animal skeletons and undertake a dive, which takes us from the primeval forest to the open sea. We then enter Xibalba – the place of myths and the dead. In the days of the Mayas - a voyage of no return. Today, this is one of the greatest challenges one can face as a diver – the hidden world of the underwater caves of Yucatan – all filmed in 3D.

The story of America's most notorious gangster, Al Capone, starts on the streets of Brooklyn. In 1913, at the age of 14, Capone starts running errands for local gangsters - just one of many immigrants struggling to survive. One day, young Al Capone gets caught in a police raid. He quickly grabs what money he can, evades police, and runs to the headquarters of mob boss Johnny Torrio. Torrio rewards Capone for his quick-thinking. When Torrio recognizes Capone's intelligence and drive, he takes him under his wing.

The definitive discourse with Noam Chomsky on the defining characteristic of our time - the deliberate concentration of wealth and power in the hands of a select few. Chomsky unpacks the principles that have brought us to the crossroads of historically unprecedented inequality - tracing a half century of policies designed to favour the most wealthy at the expense of the majority. "Requiem for the American Dream" is profoundly personal and thought provoking. Chomsky provides penetrating insight into what may well be the lasting legacy of our time - the death of the middle class, and swan song of functioning democracy. A potent reminder that power ultimately rests in the hands of the governed, "Requiem for the American Dream" is required viewing for all who maintain hope in a shared stake in the future.

Neuroscientist David Eagleman explores the human brain in an epic series that reveals the ultimate story of us, why we feel and think the things we do. This ambitious project blends science with innovative visual effects and compelling personal stories, and addresses some big questions. By understanding the human brain, we can come close to understanding humanity". In this episode, Dr. Eagleman takes viewers on an extraordinary journey that explores how the brain, locked in silence and darkness without direct access to the world, conjures up the rich and beautiful world we all take for granted.

14-year-old Laura Dekker sets out-camera in hand-on a two-year voyage in pursuit of her dream to be the youngest person ever to sail around the world alone. In the wake of a year-long battle with Dutch authorities that sparked a global storm of media scrutiny, Laura now finds herself far from land, family and unwanted attention, exploring the world in search of freedom, adventure, and distant dreams of her early youth at sea. Jillian Schlesinger's debut feature amplifies Laura's brave, defiant voice through a mix of Laura's own video and voice recordings at sea and intimate vérité footage from locations including the Galapagos Islands, French Polynesia, Australia, and South Africa.

Dr Michael Mosley seeks to establish the truth about meat. Every year, humans raise and eat 65 billion animals - nine animals for every person on the globe. In this eye-opening documentary, Michael examines the impact that this is having on the planet and finds out what meat eco-friendly carnivores should be buying. Is it better to buy free-range organic or factory-farmed meat? The answers are far from obvious.