Hidden beneath the surface of the sea is a phenomenon we know almost nothing about. On land, scientists have long studied the great animal migrations, but in the ocean some of the most spectacular events go almost unnoticed. Now, with an international team of scientists, Explorer examines the movements of hammerhead sharks to understand how they navigate, whether they possess internal compasses, and what prompts them to seek out distant destinations.

NGC counts down the top ten most terrifying sharks from around the globe. Using a specially designed "Crittercam", we'll dive into the shark world and see everything from an intimate moment between nurse sharks, to a bull shark on the prowl for its next meal. Then, we'll take you to a Mecca for great white sharks, and see them feed on one of their favorite snacks seals. From the scary, to the ugly, and the downright freakish, we'll show you what's really lurking in the darkness.

More great white shark attacks are reported along the coast of California than any other place in the world. This 135 mile-stretch called The Red Triangle is the "Grand Central" for great white sharks.

We are back off the coast of San Francisco where an unexpected killing challenged the great white shark's supremacy as the ultimate predator. We return with the whale-watchers who witnessed a stunning act of nature as a killer whale rose to the water's surface with a great white in its mouth. The outcome left biologists mystified but now, with the help of a team of experts, we re-examine this extraordinary incident, and reveal an astonishing new perspective between the ocean's two top predators.

Venture into a world of ludicrous-looking, bizarrely behaved and downright Shocking Sharks to discover a new side to these feared fish. The tasseled wobbegong uses frilled camouflage to blend into coral reef surroundings. A cigar-shaped shark has the fitting name of the cookiecutter for the way its circular jaw tears flesh from its prey. The horn shark's square, blunt head gives it its name, and the way the epaulette shark walks along the ocean floor is what makes this shark so weird.

They may be the ocean's top predators, but sharks still face great challenges at mealtime. Watch 10 remarkable shark species including whale and angel sharks on their hunt for prey in various corners of the world. Shark Kill Zone takes an in-depth look at how sharks developed their unique and cunning hunting techniques. What's the secret of their amazing success? What does it take for a shark to catch a meal?

Enter the underwater world of Mauritius and explore the mysteries of the "Shark Pits".