Forty miles north of Honduras, near the bay Island of Roatan, is a spectacular and pristine preserved coral atoll: the Mesoamerican reef. explore the abundant and diverse marine life, lush vegetation, and magnificent caves of this rare underwater wonder.

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.

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.

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.