Sunlight can penetrate the ocean for as much as about 3,300 feet (about 1,000 m) — that's why it's possible to get a sunburn while swimming. Despite this, there's rarely any significant amount of sunlight below 650 feet (about 200 m). This top 650-foot (200-m) layer is called the epipelagic zone. This zone is part of the euphotic zone, the area of the ocean in which light can penetrate. Most ocean life exists in the euphotic zone, because it is the only layer in which typical photosynthesis can occur.
More on the layers of the ocean:
- There are four ocean layers beneath the euphotic zone, starting with the dysphotic, or mesopelagic zone. This is the deepest layer that the sun can penetrate. Below the dysphotic zone there is the bathypelagic zone, the abyssopelagic zone and the hadalpelagic zones.
- Creatures below the euphotic zone often migrate upward at night to feed. These include the lanternfish, the cookiecutter shark, the stoplight loosejaw and the brownsnout spookfish.
- Pressure in the hadalpelagic zone, found in ocean trenches, is about 8 tons per square inch (1,235 kg per square cm).