English: The three primary zones of a lake are the littoral, open-water (also called the photic or limnetic), and deep-water (also called the aphotic or profundal) zones.

In limnology (the study of inland waters), a lake is divided into several distinct horizontal and vertical zones based on light penetration and proximity to the shore. The Littoral Zone is the shallow area near the shore where sunlight reaches the bottom, allowing for the growth of rooted plants. Moving toward the center, the Limnetic Zone refers to the open-water surface layer where light is still sufficient for photosynthesis (the "photic zone"). Vertically, the Profundal Zone is the deep, cold area where little to no light reaches, resulting in lower oxygen levels and different life forms. Finally, the Benthic Zone is the very bottom of the lake, consisting of sediment and home to decomposers and organisms that thrive in low-oxygen environments. In 2026, understanding these zones is critical for environmental conservation, as each zone supports a unique ecosystem and is affected differently by climate change and runoff.