Young filmmaker Julia Barnes embarks on a journey around the world to investigate the causes and solutions to some of the most pressing threats facing the oceans, such as the decimation of the world's fish populations and ocean acidification. Through interviews with scientists, researchers, and activists, the film reveals the interconnections of all life on earth, positing that the current mass extinction in the oceans will have devastating impacts on terrestrial life too, including humans. Sea of Life becomes a call to action, with the view that once more people know what's happening in the ocean, they'll want to fight for its protection. Barnes then documents some of the largest environmental rallies, including the People's Climate March in New York and protests at COP21 in Paris, but concludes that these actions will not be enough to save our future. Sea of Life calls for a revolution in the way we approach activism.