A balance in the various ecosystems around the world is what is vital for a sustainable and healthy planet.
Marine life depends in some way on the saltwater that is in the sea. A habitat is an area inhabited by one or more living species. The marine environment supports many kinds of these habitats.
Marine habitats can be modified by their inhabitants. Some marine organisms, like corals, kelp, mangroves and seagrasses, are ecosystem engineers which reshape the marine environment to the point where they create further habitat for other organisms. By volume the ocean provides most of the habitable space on the planet.
The marine environment has several different habitats with a set of specific physical factors: ocean tides, wave action, sea temperature, ocean currents, levels of light, wind, type of topography, climate.