BBC America has greenlit Blue Planet II, a new seven-part series presented by Sir David Attenborough that will take a deep dive into the world's oceans. The news comes a day after BBCA premiered Planet Earth II, a follow-up to BBC’s 2006 acclaimed nature docuseries. Blue Planet II will explore the latest frontiers of scientific discovery, from icy-white polar seas to vibrant blues of the coral atolls, from the storm-tossed green Atlantic coastline to the black depths of…