Coral reefs are nurseries of the ocean.
Healthy reefs are vital for human health.
Divers can be the difference between a healthy reef and a tragedy. Coral reefs are massive limestone structures that provide shelter for nearly one quarter of all marine life. A good way to imagine a coral reef is to think of it as a bustling city or community, with the buildings made of coral, and thousands of inhabitants coming and going, carrying out their business. In this sense, a coral reef is like a metropolis of the sea. Although coral is often mistaken for a rock or a plant, it is composed of tiny, fragile animals called coral polyps .