A story about a sea within the sea, a body of water that is warming 99% faster than the global ocean. What happens here, for the animals in the water, for the jobs dependent upon it and for the millions of people along its shores, is likely to happen worldwide. We are at a crossroads for the future of the Gulf - and our oceans. Does it retain enough of its biodiversity and regenerative strength to weather the human-induced storm? Is the sheer beauty of the place and spectacular range of its creatures enough to wake us to the stakes? A spectacular place, the Gulf of Maine is 7,500 miles long and as much as a thousand feet deep, a marine treasure of some 36,000 square miles. From the tip of Cape Cod to Nova Scotia, it courses with cold, nutrient-rich, deep-sea water, artfully mixed by the world's biggest tides. This rich environment feeds a web of 3,000 species ranging from microscopic plankton to massive right whales. Millions of people have lived along its rising edge, drawing their sustenance, fame, and fortune from its plentiful depths. It is a seminal body of water, a cradle to ancient peoples, a lifeline to fragile colonies. But for all its storied bounty, and because of it, the Gulf is also in peril, its fish stocks now depleted to possibly irreversible levels. This is an epic story blending science, exploration, stunning natural history, and stories of human experience past and future, together providing a fascinating tale about a regional location with profound global implications. In this three-hour series, encounter the spectacular wilderness and wildlife that still teem in these waters filled with jeopardy, wonder and promise. Track the stories of the scientists, Native Americans, fishers, and entrepreneurs - all working to reveal its complex history, in understanding what role the ocean plays in our lives, that ocean health equals human health.