The great Barrier Reef

The Great Barrier Reef is actually a series of smaller reefs. Reefs form under water and can be made of coral, sand, or rock. The top of the reef sits about two to three feet below sea level. Coral reefs are found in warm, shallow, clean water. The Great Barrier Reef is the largest reef of all, stretching an amazing 1,250 miles, or 2,000 kilometers, across the blue of the ocean. It forms a natural break water between the strong waves of the Pacific and the coast of Australia. It's location is in the Coral Sea, the area of the Pacific close to Australia's northeastern coast. The waters around it cover roughly 80,000 square miles, or 208,000 kilometers, an area slightly smaller than the state of Minnesota.
Reefs may be found as deep as 250 feet below the surface. Corals that grow below 150 feet don't make very good reef builders.
There are three different groups in which all reefs are classified. The first reef type is called a Fringing reef. This reef is formed as coral grows in the shallow waters along the shores of land. A barrier reef, such as the Great Barrier reef, grows some distance from the shore before coming close to the surface. A lagoon separates the barrier reef from the shore. An Atoll reef is a circular reef, usually with a lagoon in the center. The waves of the lagoon cover a submerged island. The reef grows in layers over the island.
There are many islands on the Great Barrier reef made of coral sand that has piled up to make islands. Coral sand is formed when waves constantly wash over the dead coral, breaking it in to sand. These islands have been given the name Coral Cays. Most Coral Cays are impossible to reach by boat. They are hard to see, and the sharp coral can tear out the bottom of a boat. Ancient shipwrecks can still be found among the coral!
Reefs as large as the Great Barrier Reef take thousands of years to develop. If you happen to visit a reef, any reef, be careful to not step on living coral. Most grow slowly, maybe less than two inches, or five centimeters a year. It would take years to replace it!
About three hundred fifty types of coral live and grow on the Great Barrier Reef. All have different skeleton shapes. One kind of coral looks like deer antlers! It is called staghorn coral, and is one of the more common corals on the reef. It is also one of the fastest growers. It can grow up to 4 inches, or 10 centimeters, a year!
Not only do the corals make up the reef itself, but they are home to many different creatures. Many types of fish depend on the coral to protect them.
Hundreds of miles along the reef have not been explored, but of what has, the beauty is breath taking!