Different types of spots
“Close” fringing reef
Formed near the shore, these reefs are made up of a small “lagoon” (1 to 2 meters deep) and a coral barrier a few hundred meters from the shore at the most. These small “lagoons” (they are more precisely “shallow backreef zones”) are a kind of nursery for many fish. They are reassuring and shallow, and thus ideal spots for beginners.
Narrow fringing reef
Coral sometimes colonizes the rocky or sandy seabeds right next to the coastline. Narrow reefs are formed, which are more or less dense in coral. They are recent, and characterized by the absence of coastal benches or barriers, and give rapid access to the open sea.
When a fringing reef is sufficiently developed but has not yet formed a barrier, it takes the form of a reef drop-off that is relatively abrupt, and which overlooks the open sea or a deep lagoon. The absence of a barrier means you can explore the outer slope of the reef and observe species that rarely or never venture into shallow water.
OTHER REEF TYPES
These narrow reefs are separated from the shore (sometimes by several kilometers) by a relatively deep lagoon. They form a more or less continuous reef crown around certain islands. The depth of the lagoon means many species find a home there, and the inner area is often the most interesting part to explore.
Inner reefs are located inside a lagoon (between the coast and the coral barrier), and are sometimes visible on the surface, or form around islets or sand banks. The coral formations are situated in an environment protected from waves and currents, and are often of excellent quality.
An atoll is an island shaped like a ring, made up of coral reefs and surrounding a generally shallow lagoon. They represent the oldest coral systems and are among the very richest. The outer side of the reef, open on the ocean, is the most favorable for exploration.
Sandy / grassy / rocky seabeds
These areas, situated near the coast, are generally made up of sand, seagrass, pebbles or rocks. Coral is absent, or almost, but they represent particular ecosystems that are the home to specific species.
In these deep zones far from the coast, accessible by boat during an excursion, you can sometimes see marine mammals (whales, dolphins) or whale sharks from the surface.
With an ecological aim, to combat erosion or develop fishing resources, the authorities sometimes submerge artificial reefs near the coast. They are soon colonized by undersea life and are often interesting areas to explore.