coral-reef lagoon

A coral-reef lagoon is a body of relatively shallow, calm water found in coastal environments, separated from the open ocean by a barrier such as a sandbar or a coral reef. These lagoons are typically found in tropical or near-tropical waters that support coral growth.123

Coral reefs themselves are structures built by algae and the skeletons of coral polyps, often referred to as the "rainforests of the sea" due to their rich biodiversity. Lagoons formed by coral reefs, like those found in atolls or along coastlines such as the Great Barrier Reef, are characterized by sheltered waters that support productive ecosystems with unique flora and fauna. The sediments within these lagoons are often rich in calcareous material derived from the reef structure.432