Open Ocean

Water at the Dry Tortugas with text over image reading: Includes any part of the ocean that lies away from  the shores. Majority is contained in deepest parts.  Comprised of many layers, each has unique marine life.  Found at coastal parks.

The pelagic zone, also known as the open ocean, is the area of the ocean outside of coastal areas. Here you will find some of the biggest marine life species.

Species here are affected by wave and wind activity, pressure, water temperature and prey. Since, this area spans a large distance animals have to travel far to feed. Sea turtles travel thousands of miles between breeding and feeding grounds.

NOAA Ocean Layers Graphic

Different Zones within the Pelagic Zone

The open ocean lies over the continental shelf. The seafloor is not included in the open ocean.

  • Epipelagic zone (ocean surface to 200 meters deep). This is the zone in which photosynthesis can occur, because light is available.
  • Mesopelagic zone (200-1,000m) - This is also known as the twilight zone, because light becomes limited. There is less oxygen available to organisms in this zone.
  • Bathypelagic zone (1,000-4,000m) - This is a dark zone where water pressure is high and the water is cold (around 35-39 degrees).
  • Abyssopelagic zone (4,000-6,000m) - This is the zone past the continental slope - the deep water just over the ocean bottom. This is also known as the abyssal zone.
  • Hadopelagic zone (deep ocean trenches, greater than 6,000m) - In some places, there are trenches that are deeper than the surrounding ocean floor. These areas are the hadopelagic zone. At a depth of over 36,000 feet, the Mariana Trench is the deepest known point in the ocean.


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    Last updated: May 13, 2016


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