Photic Zone

Below the photic zone, in both oceans and lakes, is the profundal zone. In the profundal zone there is still some light, but not enough to support photosynthesis. In oceans, the even deeper volume is called the abyssal zone. This volume has virtually no sunlight, and is usually deeper than 6,562 ft (2,000 m). The deepest layer of the ocean, below 19,686 ft (6,000 m), is called the hadal zone. All of these zones receive a constant rain of organic debris and wastes from the photic zone which serves as a food source for the organisms living in the deeper volumes.

All of these are open-water zones, as compared with the shallow areas near the edges of oceans and lakes, called the coastal and littoral zones, respectively. Most of these smaller, shallow areas receive sufficient sunlight to allow plant productivity to occur right down to the lake or ocean bottom.