What is the term for the layer of ocean water that is partially affected by sunlight?

The term for the layer of ocean water that is partially affected by sunlight is the photic zone. This zone is characterized by sufficient light penetration that supports photosynthetic organisms, such as phytoplankton. The photic zone typically extends from the surface of the ocean to a depth where light intensity is low enough that photosynthesis becomes unviable, generally around 200 meters (656 feet) in deep oceanic waters.

In contrast, the aphotic zone lies below the photic zone and receives no sunlight, making it inhospitable for photosynthesis. The deep sea zone refers to regions of the ocean that are beyond the continental shelf, where light does not penetrate, thereby overlapping with the aphotic zone. The surface layer is a more general term that may refer to the upper part of any body of water and does not specifically denote the region where light has a significant impact on biological activity. Thus, the photic zone specifically identifies the light-affected area where most oceanic life thrives due to the availability of sunlight.