Which ocean zone receives enough sunlight for most marine photosynthesis?

The photic zone is the ocean zone that receives enough sunlight for most marine photosynthesis.

Light is strongest at the surface and decreases rapidly with depth because seawater absorbs and scatters it. The photic zone therefore has no single universal depth. In clear open ocean water it may extend to roughly 200 metres, while particles, plankton, and coastal sediments can make it much shallower.

Phytoplankton, seaweeds, and seagrasses depend on this illuminated layer to convert light energy into chemical energy. Their productivity supports food webs ranging from tiny zooplankton to large fish and whales. Most ocean oxygen production begins with photosynthetic organisms in sunlit waters.

The photic zone is different from the euphotic zone in some technical usages, although the terms are often treated similarly in general descriptions. Below the illuminated layer, animals may still survive by eating falling organic matter or other organisms, but photosynthesis becomes severely limited or impossible.