Patch Reefs

 

Patch reefs are usually found near one of the major types of coral reefs; their tops are just below the surface of the water, and at low tide their tops may be above the surface of the water. Patch reefs are small isolated reef formations that are circular or oval in shape. Patch reefs develop in calm protected waters behind barrier reefs. Gradually the reefs drop down and the coral continues to grow. If the reefs drop down completely you see a reef around a lagoon. This is called an atoll.