reefs
n. countablen. long lines of rocks, sand, or coral that sit just below or above the surface of the ocean. They are often home to many different types of fish and sea life.
n. ridges of jagged rock, coral, or sand located at or near the surface of the water. Often refers specifically to coral structures that support diverse marine ecosystems.
The boat hit the reefs near the shore.
Divers travel from all over the world to explore the colorful coral reefs and see the tropical fish.
Environmental scientists are monitoring how rising ocean temperatures affect the health of these delicate reefs, which serve as vital barriers against coastal erosion during major storms.
Usually used in the plural when referring to large underwater systems or geographical features.