What type of coral reef is directly attached to the shoreline?

A coral reef directly attached to the shoreline is called a fringing reef. It may grow right from the coast or sit beside it with only a narrow, shallow channel or lagoon in between.

Fringing reefs are the most common major reef type. They often begin growing near the low-water shoreline and gradually expand seaward as coral colonies, algae, shells, and other reef material accumulate. Their width depends partly on how quickly the seabed drops into deeper water.

This structure distinguishes fringing reefs from barrier reefs, which are separated from land by a deeper, wider lagoon, and atolls, which generally form ring-shaped reefs around a lagoon with little or no central land. Naturalist Charles Darwin proposed that fringing reefs could develop into barrier reefs and eventually atolls as volcanic islands slowly subsided.

The Ningaloo Reef in Western Australia is often cited as the world’s largest fringing reef, stretching for roughly 260 kilometres along the coast.