Definitions for "Photic zone"
The zone extending downward from the OCEAN surface within which the light is sufficient to sustain photosynthesis. The DEPTH of this layer varies with water clarity, time of year and cloud cover, but is about 100 m in the open OCEAN. It may be considered the DEPTH to which all light is filtered out except for about one percent and may be calculated as about two and one-half times the DEPTH of a SECCHI DISK reading.
The depth zone in the ocean extending from the surface to that depth permitting photosynthesis; usually less than 100m.
Literally, zone with light. The photic zone is part of the marine pelagic zone and extends to 600 feet below the surface of the ocean. Photosynthetic plankton as well as bony fish, sharks, and whales inhabit this zone.