Watch Nature Season 41 Episode 12 Online

In 2013, a fisherman in Guatemala, who is struggling to feed his family, is forced further offshore in a search for food. In an act of desperation, he guns his small boat straight out to sea and into dangerous waters. With no land in sight, the sun blazing, the fisherman cuts his engine and peers over the side of his boat. His expression transforms to utter disbelief. He is sitting atop a coral reef, five times the size of Manhattan and teeming with life, that no one knew existed. It is like a window back in time when Caribbean corals were thriving. The discovery is part of an even bigger story, marking an exciting new chapter in understanding corals, the fish that need them and the battle to save coral reefs all over the world.