What are the three types of coral reefs?

1. Fringing reefs: These reefs are directly attached to the shoreline, and they usually extend seaward for only a short distance. They are most common in tropical regions, where the water is clear and shallow.

2. Barrier reefs: These reefs are separated from the shoreline by a lagoon of open water. They are most common in the Caribbean Sea and the Pacific Ocean.

3. Atoll reefs: These reefs are ring-shaped, and they are usually found in the middle of the ocean. They are most common in the Indian Ocean and the Pacific Ocean.