1Did you know that most of Earth's oxygen comes from the marine biome? The marine biome is the largest biome in the world. This biome includes the five main oceans and is a source of food, air, and water for plants, animals, and people all over the world. Learn about the geography and resources of the marine biome as well as how animals and people have adapted to and impacted marine environments. Explore this biome's future and what people can do to help keep it safe.