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.

Jerusalem immerses audiences into one of the world's most beloved cities. Discover why this tiny piece of land is sacred to three major religions through the stories of Jewish, Christian and Muslim families who call Jerusalem home. Join renowned archaeologist, Dr. Jodi Magness, as she travels underground to solve some of this city's greatest mysteries. Find out why, after thousands of years, Jerusalem and the Holy Land continue to stir the imagination of billions of people. Unprecedented access to the city's holiest sites, as well as rare and breathtaking aerial footage of the Old City, combine to make Jerusalem a unique and stunning cinematic experience.

Horizon discovers what your cat really gets up to when it leaves the cat flap. In a groundbreaking experiment, 50 cats from a village in Surrey are tagged with GPS collars and their every movement is recorded, day and night, as they hunt in our backyards and patrol the garden fences and hedgerows. Cats are fitted with specially developed cat-cams which reveal their unique view of our world. You may think you understand your pet, but their secret life is more surprising than we thought.

Amazing Ocean is a fantastic journey through the magic of the deep blue sea. Let yourself be amazed by little schools of fish that swim right into your living room. See squids and the elusive octopus up close, along with the magnificent manta ray, and experience dolphins and turtles that visit you in your sofa. Shot in stereoscopic 3D, the film is a breathtakingly beautiful experience. Directed by Benjamin Eicher and Timo Joh. Mayer.

One Life on the Limit is an action documentary showcasing the glamour, speed, danger and excitement of Formula One Grand Prix racing. Narrated by Michael Fassbender, the film tells the story of the golden age of Formula 1, when the sport became terrifyingly dangerous. In the late 1960s, Formula 1 cars doubled their engine size and sprouted wings, making them incredibly quick, but even more hazardous. With money pouring in from sponsorship and a new worldwide television audience, superstar drivers were born, thrown like gladiators into the ring. The drivers were legendary with charisma and raw talent, but many of them paid the ultimate price. Follow the story of the drivers who raced on the edge and those who stood up to change the sport forever. It is about the greatest show on earth, Formula 1.

'Flexing' is a dance style forged in far east Brooklyn, at the dead-end of a handful of subway lines. Flex dancers channel the grittiness and crime of East New York into choreographed violence with gun movements, simulated bone-breaking, and the mimicked ripping of hearts from opponent's chests. Through battles dancers gain respect, craft an artistic identity, and sometimes find a sanctuary from the poverty and violence that saturates their neighborhood. No other style of street-dance is this violent, scary, or beautifully theatrical. In this purely do-it-yourself scene, creativity and ambition bring a community together around frequent dance-battle showcases that have begun to attract an international audience and may catapult the best dancers into careers in theater or film. Following a group of dancers for over two years, Flex is Kings explores the hopes and realities of this under-acknowledged and totally unfunded group of urban artists