Blue Realm

The remote and barren Socorro Islands offer little refuge to humans, but they are a magnet to migrating fish, whales and large sharks. This program focuses on the archipelago's most intriguing residents, giant manta rays, their unusual behavior and surprising intelligence.

Do squid and octopus talk with their skin? This program joins scientists in a remarkable quest to unravel the secrets of one of the sea's most enigmatic creatures, cephalopods. The episode features the bizarre behavior and sexual rituals of Caribbean reef squid, giant octopus of the Pacific Northwest and cuttlefish at the National Resource Center for Cephalopods in Galveston, Texas.

Each year, hundreds of critically endangered manatees are killed in U.S. waters by boats, disease and cold weather. With only a few thousand remaining in the wild, the clock is ticking in efforts to save this amazing mammal from extinction.

Humpback whales were hunted to the brink of extinction until a moratorium was implemented in the 1980s. After finally rebounding in numbers, whaling nations are exploring ways to re-open the hunt. In Antarctica, Japan is targeting minke, fin and now...humpbacks.

Since the 1970's, sea lion populations have declined more than 80% along the North Pacific coast. Scientists at the University of British Columbia and the Vancouver Aquarium are working together to help save Canada's iconic and largest pinniped - the stellar sea lion.

They're beautiful...and deadly, with large, venomous spines that resemble a lion's mane. They're lionfish - a tropical reef species normally found in the Pacific. Now, they're wreaking havoc in the Caribbean and Atlantic - all thought to have descended from a handful of aquarium fish carelessly released into the sea.

Around the globe, thousands of decommissioned naval vessels rot in dockyards. What can you do with these toxic time bombs? One solution is to clean them well, blow them up and sink them! Providing shelter and breeding grounds, countless fish and invertebrates colonize steel hulls.

The waters of Papua, New Guinea and Australia's Great Barrier Reef are among the richest on Earth. Harbouring an exceptional variety of venomous fish, reptiles and invertebrates, their coral reefs conceal frightening secrets. The poisons of these animals are some of the most lethal known to man, but they also hold enormous potential in the development of new medicines.

There's no doubt sharks have an image problem. And they're certainly in trouble globally. The population of some species has declined by more than 90% due to over fishing. But there's still one place in the world where sharks thrive - the Bahamas. Sharks not only prosper there, they are highly protected. It's one of the few places in the world where killing a shark is illegal.

They're floating junkyards...moth-balled, decommissioned naval vessels, rotting away in dockyards around the world. Cutting them up for scrap is expensive, and leaving them to fall apart where they are is an ecological nightmare. Sounds like a job for...The Shipsinkers.

Believe it or not, many scuba divers want to see great whites up close, and photographers want dramatic shots. But how do you get the sharks to where you want them? For decades, it's been done by baiting, or "chumming" - attracting sharks with food. This practice is being questioned and banned in many countries because of a dramatic increase in shark attacks.