The vibrant reef ecosystem of Raja Ampat, off the coast of Indonesia, is home to a conservation sanctuary twice the size of Singapore. It's one of the few places on Earth where two different species of manta ray live side by side. Join a dedicated team of conservationists as they track these mysterious creatures to safeguard their future.

Indonesia's marine rainforests are under threat, and rising sea temperatures and destructive fishing practices have taken a toll. However, conservation initiatives in hundreds of protected marine zones have given hope to the giant manta rays, 300 species of coral, and six of the world's seven sea turtle species that call this ecosystem home.

Beneath Indonesia's coral reef, tiny creatures have made the murky seabed their home. Here, you'll find shrimps that kill with a whip-fast punch, toxic nudibranch sea slugs, and six of the nine species of the world's walking sharks. Dive into the depths of this unlikely ocean ecosystem.

The Maldives are the lowest country in the world--and getting lower, due to rising sea levels. Especially at risk is the island's reef system, the biggest in the Indian Ocean, with over 200 types of coral and thousands of tropical fish species. Witness the race to preserve this marine paradise from the ravages of climate change.

The Pacific coast of Costa Rica is home to an astonishing 3.5% of all marine species in the world. Helping keep things in check is the region's apex predator, the hammerhead shark, whose dwindling numbers present a major threat to the health of the ecosystem. Witness the efforts to keep this mighty creature alive.

Mantas eat plankton, not fish. So why would oceanic manta rays, among the largest of the species, make an annual pilgrimage from the waters of Mozambique all the way to the coast of South Africa to attend the sardine run, the world's largest migration of marine animals? Follow dedicated manta researchers as they work tirelessly to discover the secrets of one of the ocean's most mysterious and majestic dwellers. They might even discover new species along the way.

The 1,600-mile coast of Mozambique is a magnet for the world's largest marine dwellers, from manta and sting rays to sharks and dolphins. While manta ray numbers are impacted by a migration path that overlaps with their predators, the biggest threat comes from bad fishing practices. Join marine specialists Andrea and Nakia as they set out to identify the favored habitats of manta rays, learn about their migratory habits, and devise strategies to protect the species from catastrophic decline.

The coastal waters of Mozambique are the domain of giants, from visiting humpbacks to resident whale sharks. But the tiniest species also play a big role. Brightly colored slugs known as nudibranchs inhabit shallow reefs, estuaries, and mangroves. Of the 200 species here, 90% are newly discovered. Follow the research team as they navigate fickle tides and indiscriminate fishing practices to protect the marine giants of Mozambique--and the tiny creatures that live in their shadow.

To a marine biologist, any attempt at mapping an oceanic food chain begins and ends with plankton, from tiny bacterial algae to soft-bodied animals such as jellyfish. These microscopic miracles are responsible for producing two-thirds of atmospheric oxygen. Their place at the bottom of the chain has the greatest impact on marine life, whether they're providing nourishment for filter-feeders such as sardines and manta rays or predators like dolphins and sharks.