Sir David Attenborough reveals the findings of one of the most ambitious scientific studies of our time - an investigation into what is happening to our oceans. He looks at whether it is too late to save their remarkable biodiversity. Attenborough explores some of the ways in which we are affecting marine life - from over-fishing to the acidification of sea water. The film also uncovers the disturbing story of how shipping noise is deafening whales and dolphins, affecting their survival in the future.

Particle physicist Prof. Brian Cox asks, 'What time is it?' It's a simple question and it sounds like it has a simple answer. But do we really know what it is that we're asking? Brian visits the ancient Mayan pyramids in Mexico where the Maya built temples to time. He finds out that a day is never 24 hours and meets Earth's very own Director of Time. He journeys to the beginning of time, and goes beyond within the realms of string theory, and explores the very limit of time. He discovers that we not only travel through time at the speed of light, but the experience we feel as the passing of time could be an illusion.

The drug policies have remained unchanged over the last 40 years so should they be reformed in the light of new research? Recent research has analysed the link between the harmful effects of drugs relative to their current classification by law with some startling conclusions. Perhaps most startling of all is that alcohol, solvents and tobacco (all unclassified drugs) are rated more dangerous than ecstasy, 4-MTA and LSD (all class A drugs).

Attenborough's journey continues in Canada's Rocky Mountains, where fossils document an explosion in animal diversity never seen before or since. Travelling from there to North Africa, the rainforests of Australia and the east coast of Scotland, Attenborough discovers how animals evolved to conquer not only the oceans but also the land and air. These remote and fascinating creatures are brought to life as never before with the help of cutting-edge scientific technology and photorealistic visual effects. From the first large predators to the first legs on land, these were creatures that evolved the traits and tools that allow all animals, including ourselves, to survive to this day.

Hernan Cortes left Cuba in 1519 seeking riches in the island to the west. Instead he discovered, and ultimately destroyed, a hitherto unknown civilization. Join Micheal Wood as he retraces this fateful expedition. Read Spanish eyewitness accounts that describe the conquistadors' awe at the Aztec achievements and the lust for native treasure. Learn the Aztec' side of the story by scrolling trough pictographs that tell of the agonizing fall of the empire.

Just 92 elements made up the world, but the belief that were only four - earth, fire, air and water - persisted until the 19th Century. Professor Al-Khalili retraces the footsteps of the alchemists who first began to question the notion of the elements in their search for the secret of everlasting life.He reveals the red herrings and rivalries which dogged scientific progress, and explores how new approaches to splitting matter brought us both remarkable elements and the new science of chemistry.