For admirers of exotic lands, coral reefs are the landscape of their dreams. When one thinks of coral reefs, he starts dreaming of sunny beaches with crystal waters.

Corals live in the hot seas (mostly in the latitudes of 30 degrees north and south of the Equator where water temperature is between 18 and 30 C). Coral reefs are constituted of the skeletons of tiny organisms, called polyps. It is these microscopic organisms, which grow at a slow pace over the years, that develop the reefs.

It is estimated that reefs cover 0.2% of the area of oceans, and they are the home of many marine species. For countries with coral reefs, like Japan, Egypt and Australia, they are a major tourist attraction.

There are several classifications of coral reefs, but the most popular divides them in four groups: fringing reefs, platform reefs, barrier reefs, and atolls.

Fringing reefs occur in shallow waters near the shore. They can be separated from the shore by a narrow strip of water, while platform reefs are pretty far away from the shore. Platform reefs are flat (like a platform).

Barrier reefs are formed parallel to the coastline and a separated from it by a lagoon. These reefs are often very big for instance, the Great Barrier Reef in Australia is over 2,300 kilometers long and its surface covers over 200,000 square kilometers.

The last variety of coral reefs is the atolls. They are circular in form and encircle an island. Usually atolls have a lagoon in the middle. Atolls are deep sea if they rise from the ocean, and continental when they are found on the continental shelf.