David Attenborough returns to the island of Madagascar on a very personal quest. In 1960, he visited the island to film one of his first ever wildlife series - Zoo Quest. Whilst he was there, he acquired a giant egg belonging to an extinct bird known as the 'elephant bird' - the largest bird that ever lived. It has been one of his most treasured possessions ever since. Fifty years older, he now returns to the island to find out more about this amazing creature and to see how the island has changed. Could the elephant bird's fate provide lessons that may help protect Madagascar's remaining wildlife?
Using Zoo Quest archive and specially shot location footage, this film follows David as he revisits scenes from his youth and meets people at the front line of wildlife protection. On his return, scientists at Oxford University are able to reveal for the first time how old David's egg actually is, and what that might tell us about the legendary elephant bird.

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.

The Sea of Cortez, also known as the Gulf of California, is a unique corner of the Pacific Ocean. This remarkable young sea is thought to be around five million years old and home to nearly 900 species of fish and the widest variety of whales and dolphins found anywhere on Earth. Some of the greatest changes threatening the world's oceans today can be seen in this stretch of water.

The Southern Ocean, which circles the globe without being blocked by land, is home to the Antarctic Circumpolar Current (ACC), the longest of the world's ocean currents. Also known as the "channel", it connects the Indian, Atlantic and Pacific Ocean basins and exerts a powerful influence over the Earth's climate. The ACC carries 150 times more water around Antarctica than the flow of all the world's rivers combined.

The Red Sea is one of the youngest oceans in the world and one of the warmest. The northern region, with its diverse array of marine life, is one of the most visited dive locations on earth while the southern end remains virtually unexplored. It's a global hotspot for marine biology and an important trade route throughout human history, linking the trade goods of India and the Far East with the markets of Egypt and Europe.

The Indian Ocean is the third largest body of water on Earth at more than 6,000 miles wide and covering 13% of the world's surface. It is home to 5,000 species of fish, many of which only exist in the Indian Ocean. But it is also an ocean under threat from global issues such as over-fishing and climate change, which make this an ocean on the edge.