Coral reef a protective area, or it may lie between the reef and the shore, and in this case is a flat, rocky area. Fish tend to prefer it when it is present. The reef lagoon is an entirely enclosed region, which creates an area less affected by wave action and often contains small reef patches. However, the "topography of coral reefs is constantly changing. Each reef is made up of irregular patches of algae, sessile invertebrates, and bare rock and sand. The size, shape and relative abundance of these patches changes from year to year in response to the various factors
Open-water diving water, with various constraints regarding the conditions, and particularly that their competence is limited to diving in open water of with free access to the surface. Open-water diving In underwater diving, open water is unrestricted water such as a sea, lake or flooded quarries. It is the opposite of confined water (diving) (usually a swimming pool) where diver training takes place. Open water also means the diver has direct vertical access to the surface of the water in contact with the Earth's atmosphere. Open water diving implies that if a problem arises, the diver can directly ascend vertically to the