---
title: "Photic Zone — AP Environmental Science Definition & Exam Guide"
description: "The photic zone is the sunlit top layer of water where photosynthesis happens. Learn why it drives marine productivity and how sea level rise threatens it on the AP Enviro exam."
canonical: "https://fiveable.me/ap-enviro/key-terms/photic-zone"
type: "key-term"
subject: "AP Environmental Science"
---

# Photic Zone — AP Environmental Science Definition & Exam Guide

## Definition

The photic zone refers to the upper layer of a body of water where sunlight can penetrate sufficiently for photosynthesis to occur. It is characterized by high levels of light availability.

## Related Study Guides

- [9.5 Global Climate Change](/ap-enviro/unit-9/global-climate-change/study-guide/7uD60uqTmhzrFIlNVpw9)
- [1.3 Aquatic Biomes](/ap-enviro/unit-1/aquatic-biomes/study-guide/Ka0nsiIoWMSAbSKgVUqC)

## Review

### Related Terms

- [Aphotic Zone](/ap-enviro/key-terms/aphotic-zone): The deeper layer in a body of water where little or no sunlight penetrates, making it impossible for photosynthesis to occur.
- [Phytoplankton](/ap-enviro/key-terms/phytoplankton): Microscopic plant-like organisms that float near the surface in the photic zone and form the base of many aquatic food chains.
- Light Intensity: The amount or strength of light present in a particular area within the photic zone.