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 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.