The surface waters of an ocean or lake that receive sufficient solar radiation to support photosynthesis, (i.e. the growth of vascular plants and phytoplankton). When sunlight falls on the surface of a lake or ocean, a large part of the light is reflected, scattered, or absorbed. Some light penetrates the water, but its intensity decreases quite rapidly with depth. The photic zone can be up to 328 ft (100 m) deep, and, typically, its limit is reached when the light intensity falls below one percent of the incident radiation.