How deep are most coral lagoons?

Most coral lagoons are relatively shallow, with depths that rarely exceed 60 metres (about 200 feet). Many are even shallower, typically measuring less than 20 metres (about 65 feet) in depth.1

While some specific examples, such as the lagoon of Mayotte in the Indian Ocean, can reach greater depths—up to approximately 92 metres (about 300 feet)—these are generally exceptions. The depth of these environments is often maintained by a balance between sedimentation and the subsidence of the underlying foundation, allowing the coral to continue its upward growth.12