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.

Visit the planet most like Earth. There is a discussion of what life on Mars would be like and about the life forms that could've evolved there

In the final challenge of the game of life, raising offspring is the ultimate prize. Continuing the line through the next generation, is the next best thing to immortality. But it’s far from easy... Some parents must risk their own lives for their offspring.

The story of how an eccentric French shop keeper and amateur film maker attempted to locate and befriend Banksy, only to have the artist turn the camera back on its owner with spectacular results. Billed as 'the world's first street art disaster movie' the film contains exclusive footage of Banksy, Shephard Fairey, Invader and many of the world's most infamous graffiti artists at work. No director or screenwriters are listed in "Gift Shop's" credits, just the words "A Banksy Film." Banksy is a graffiti artist with a global reputation whose work can be seen on walls from post—hurricane New Orleans to the separation barrier on the Palestinian West Bank. Fiercely guarding his anonymity to avoid prosecution, Banksy has so far resisted all attempts to be captured on film. Exit Through the Gift Shop tells the incredible true story of how an eccentric French shop keeper turned documentary maker attempted to locate and befriend Banksy, only to have the artist turn the camera back on its owner – with spectacular results. The film contains exclusive footage of Banksy, Shepard Fairey, Invader and many of the world's most infamous graffiti artists at work, on walls and in interview. As Banksy describes it, "It's basically the story of how one man set out to film the un—filmable. And failed."

Hawking is the extraordinary story of the planet's most famous living scientist, told for the first time in his own words and by those closest to him. Made with unique access to Hawking's private life, this is an intimate and moving journey into Stephen's world, both past and present. An inspirational portrait of an iconic figure, Hawking relates his incredible personal journey from boyhood under-achiever, to PhD genius, to being diagnosed with Motor Neuron Disease and given just two years to live. Despite the constant threat of death, Hawking manages to make many remarkable scientific discoveries and rises to fame and super-stardom. Hawking - a remarkable man, and a remarkable movie.

This episode provides an overview of the nature of electromagnetism, as discovered through the work of Michael Faraday. Tyson explains how the idea of another force of nature, similar to gravitational forces, had been postulated by Isaac Newton before. Tyson continues on Faraday, coming from poor beginnings, would end up becoming interested in studying electricity after reading books and seeing lectures by Humphry Davy at the Royal Institution. Davy would hire Faraday after seeing extensive notes he had taken to act as his secretary and lab assistant. After Davy and chemist William Hyde Wollaston unsuccessfully tried to build on Hans Christian Ørsted's discovery of the electromagnetic phenomena to harness the ability to create motion from electricity, Faraday was able to create his own device to create the first electric motor by applying electricity aligned along a magnet. Davy, bitter over Faraday's breakthrough, put Faraday on the task of improving the quality of high-quality optical glass, preventing Faraday from continuing his research. Faraday, undeterred, continued to work in the Royal Institution, and created the Christmas Lectures designed to teach science to children. Following Davy's death, Faraday returned to full time efforts studying electromagnetism, creating the first electrical generator by inserting a magnet in a coil of wires. Tyson continues to note that despite losing some of his mental capacity, Faraday concluded that electricity and magnetism were connected by unseen fields, and postulated that light may also be tied to these forces. Using a sample of the optical glass that Davy had him make, Faraday discovered that an applied magnetic field could affect the polarization of light passing through the glass sample (a dielectric material), leading to what is called the Faraday effect and connecting these three forces. Faraday postulated that these fields existed across the planet, which would later by called Earth's magnetic field generated by the rotating molten iron inner core, as well as the phenomena that caused the planets to rotate around the sun. Faraday's work was initially rejected by the scientific community due to his lack of mathematical support, but James Clerk Maxwell would later come to rework Faraday's theories into the Maxwell's equations that validated Faraday's theories. Their combined efforts created the basis of science that drives the principles of modern communications today.