The limnetic zone is the well-lit, open surface waters in a lake, away from the shore. The vegetation of the littoral zone surrounds this expanse of open water and it is above the profundal zone

Profundal zone

The profundal zone is a very cold and ordinary zone, such as an ocean or a lake, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly...

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It can be defined as the lighted surface waters in the area where the lake bottom is too deep and unlit to support rooted aquatic plants. This area is not occupied by a variety of phytoplankton

Phytoplankton

Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

, consisting of algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and cyanobacteria, as well as zooplankton

Zooplankton

Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

, small crustaceans, and fish.