Discover the world's ocean--from tides and currents to the creatures living in it to the impact it has on our lives, whether we know it or not--in this richly illustrated overview of the life force that defines and sustains our planet, written by world-renowned oceanographer Sylvia Earle.  Everything you want to know about the ocean can be found inside these beautiful and dynamic pages. National Geographic Ocean unveils the power and significance of our planet's watery essence: the fundamental importance of the ocean in shaping Earth's climate and chemistry as well as its vital role in supporting a multitude of life-forms, including our own human race.   World-renowned oceanographer and National Geographic Explorer in Residence Sylvia Earle--affectionately called 'Her Deepness'--guides readers with her lyrical style and inspiring wisdom, describing the evolution, beauty, and impact of our ocean; the challenges it faces, such as climate change, plastic, and overfishing; and the myriad