The uppermost layer of the world’s oceans is bathed in sunlight during the daytime.
This bright ocean layer is called the sunlit zone or the euphotic zone (euphotic means well lit in Greek) or the epipelagic zone (epipelagic means upon the sea).
The depth of this zone depends on the clarity or murkiness of the water.
In clear water the euphotic zone can be quite deep; in murky water it can be only 50 feet deep.
On average it extends to about 200 meter); the depth of the ocean averages about 4000 m.
The temperature in this zone ranges from 104 to 27 degrees F.