Jonathan Bird's Blue World

In this video extra, Jonathan explores the various kinds of toothed whales and how dolphins are just small whales.

Jonathan joins Charlie Donilon on his shark charter boat in Rhode Island, Massachusetts, and learns about how shark tagging has shed light on the biology of and behavior of Blue sharks. Tagging has shown that these incredible swimmers actually migrate completely across the Atlantic ocean. Jonathan tries his hand at tagging a shark and then swims with Blue sharks. We also learn that Blue sharks are not nearly as vicious as they have been reputed to be, and the divers are actually able to pet the sharks!

In this video extra, Jonathan explains what a pelagic shark is and why Blue sharks are considered pelagic.

In a quiet forest in central Florida, a mysterious pond filled with warm, clear water hides a secret at the bottom. Jonathan explores the pond to find a spring which leads into a cavern. As Jonathan travels underground, he meets unexpected life in the dark depths.

In this video extra, Jonathan discusses the dangers and techniques involved in overhead environment diving, such as cave diving, cavern diving, wreck diving and ice diving.

The Sperm whale holds many records. It is the deepest-diving whale on Earth, the largest toothed whale on Earth and has the largest brain on the planet too. On top of that, it has a reputation for being a vicious beast, thanks in part to Herman Melville's Moby Dick. But the Sperm whale is a lot different than people think. It has a highly-evolved social life, operates at depths where nobody can see them most of the time, and uses sonar which is so sophisticated that it makes the Navy's electronics look like toys. Sperm whales are very hard to find and even harder to shoot, but Jonathan knows where to go to film the intimate social relationships of these giants.