Hypolimnion

The hypolimnion is the bottom and most dense layer of water in a thermally-stratified Lake. It is the layer that lies below the Thermocline. Typically, it is non-circulatory and remains cold throughout the year.

Typically the hypolimnion is the coldest layer in the summer and the warmest during winter. Being at depth, it is isolated from surface wind-mixing and is does not receive enough incoming irradiance (light) for photosynthesis to occur.

See also: Epilimnion