America's vast ocean realm spans nearly 4.5 million square miles, an area 23 percent larger than the land area of the United States. A rich tapestry of marine life inhabits these waters from the swift bluefin tuna in Atlantic waters to centuries-old deep sea corals in the depths of Alaskan waters. And though our oceans are immense, recent scientific evidence shows they are highly vulnerable and threatened by habitat destruction, pollution and overfishing.