There are more than 200,000 known species in the ocean, but there is thought to be more than 2 million more that remain undiscovered. Humans have only explored 5 percent of Earth’s oceans, so what else could be lurking deep beneath the surface? In this bite-sized curated collection, Seeker dives in to explore the deepest parts of the oceans, how they get polluted and how scientists discovered a hidden ocean in the most unusual place.