Coastal waters host fringing reefs that cling to shorelines, separated from the land by a narrow, shallow lagoon, making them highly vulnerable to human activities. Further out, barrier reefs extend parallel to the coast with a deeper and wider lagoon that can even reach the surface, impeding navigation, as seen with Australia’s renowned Great Barrier Reef. Volcanic islands give rise to circular atolls with a central lagoon connected to the open sea through natural gaps, illustrating the dynamic formation of reef ecosystems. Additionally, smaller patch reefs often dot these larger structures, contributing distinct, lower formations within the marine landscape.