Great Blue Wild

The Pacific coast of Costa Rica hosts nearly 5,000 species of marine life. But in this undersea jungle, the apex predator sharks are at risk. (S2, ep 8)

In a unique part of the African coast, manta ray researcher Andrea Marshall hopes to conduct the first ray expedition within South Africa's borders. (S3, ep 1)

Some of the world's largest filter feeders are attracted to Mozambique's nutrient-rich water. But even these behemoths are vulnerable to rampant over-fishing. (S3, ep 2)

It is the smallest of creatures that underpins the ocean's food web - plankton. Without them, marine life as we know it would cease to exist. But why? (S3, ep 4) Also in UHD.

The coast of Mozambique is known for its giants, from visiting humpbacks to the resident whale sharks. But just as important are the water's tiny creatures. (S3, ep 3)