The ocean twilight zone, also called the mid-water or the mesopelagic, lies far beneath the sunlit surface waters. It’s defined not by depth, but by the amount of light that penetrates the water above it: during the day, there is just enough light for animals to see, but it is far too dim for any plant life to grow. Depending on the clarity of the water, the zone is generally considered to be about 200 to 1,000 meters (650 to 3,300 feet) below the surface. It stretches around the world from the Arctic to the Antarctic and exists mainly in the “high seas” beyond the control of any one nation.
The twilight zone is a fundamental part of the ocean that has great benefit to humans.
