The littoral zone extends from the shoreline to 600 feet (183 meters) out into the water. This area of the ocean contains high-energy waves and tidal motions that influence both human and marine activity.
The littoral zone is broken into three main subcategories: the supralittoral, the eulittoral and the sublittoral zones. All of these zones have an abundance of dissolved oxygen, sunlight and nutrients that nurture sea life.
The supralittoral zone is also commonly referred to as the splash zone. This area is characterized by regular interaction with the spring high tide. This area is exposed to several different environmental conditions, like open air, temperature fluctuation, seawater and fresh water from streams and rivers. There is a high level of competition among biological lifeforms like seabirds, amphibians and crustaceans.
The eulittoral zone is also called the midlittoral zone. This subzone extends from the spring high tide to the neap low tide line. The action of tidal waves shapes coastal caves and cliffsides, providing habitats for barnacles and sedentary organisms.
The sublittoral zone has a depth of about 200 meters and extends to the end of the continental shelf. The preponderance of sea life exists in the sublittoral zone, because at this depth sunlight can still reach the seafloor.