What will we find in the twilight zone: the vast, mysterious, virtually unexplored realm hundreds of meters below the ocean's surface? Heidi M. Sosik of Woods Hole Oceanographic Institution wants to find out. In this wonder-filled talk, she shares her plan to investigate these uncharted waters, which may hold a million new species and 90 percent of the world's fish biomass, using submersible technology. What we discover there won't just astound us, Sosik says -- it will help us be better stewards of the world's oceans. (This ambitious idea is part of the Audacious Project, TED's initiative to inspire and fund global change.)