August 26, 1768 The HMS Endeavour , under the command of Captain James Cook, set sail from England. The British Royal Navy, and a scientific group called the Royal Society of London, were sending Cook halfway across the globe--to the South Pacific island of Tahiti. Why? With an astronomer and other scientists, Cook was to record the passage of the planet Venus across the face of the sun. They would compare their measurements to measurements other astronomers were taking around the world. This would help them figure out the distance between the earth and the sun. Months later, in June 1769, the work in Tahiti was done. But Captain Cook was not going home. Not yet. He had been given a sealed letter before he left England. Now he could open it. The letter contained a set of orders for a second mission--a secret mission. Cook was to sail from Tahiti to a place known only as Terra Australis Incognita . This is Latin for "Unknown South Land." Today, we call it Australia. Forty-year-old Captain Cook was a very experienced sailor and explorer. The British Royal Navy wanted him to explore Australia's east coast. No European had ever seen this land. On April 19, 1770, the Endeavour reached this part of Australia. Cook later named it New South Wales and claimed it for England. Captain Cook continued north along the coast. He didn't know he was about to make another great discovery--a dangerous discovery. Late on June 11, under a bright moon, the Endeavour crashed into something rock solid! The ship became stuck! Cook and his crew were twelve miles from shore. They tried to move the ship back into deep water by lightening the ship's load. They threw as much as fifty tons of cannons, coal, and cargo overboard. They waited until morning, hoping that the high tide would lift the ship. But it stayed stuck. A leak sprung. Water poured into the ship. For the next twelve hours, the men scrambled to save their ship. They took turns at the pumps, trying to push seawater out as fast as it poured in. One sailor filled a canvas sail with wool and sheep's dung and used it to help plug the leak. Around ten o'clock that night, high tide arrived again. The crew was able to guide the Endeavour off its rocky ledge and back into deep water. They were saved! This "rocky ledge," however, was not actually rock at all. It was a coral reef. Coral is made up of millions of tiny animals called polyps (PAWL-lups). This coral reef was one of three thousand reefs that make up the Great Barrier Reef. For more than six weeks, Captain Cook and his crew repaired the Endeavour onshore. More than two months after the crash, Cook was finally able to steer the ship through the Reef and out into the open ocean. Captain Cook's "discovery" of the Great Barrier Reef was only the beginning. Ever since, this miracle of nature has captured the imagination of explorers, scientists, and tourists alike. Today, more than a million people visit the Great Barrier Reef each year. And we've only just begun to understand it. Chapter 1 : Islands from Hilltops The Great Barrier Reef is enormous. It is the largest living structure on earth. It is so big, it can be seen from outer space! From high above the earth, it looks almost like a line of turquoise-colored toothpaste between the green of Australia and the deep blue of the Pacific Ocean. Closer up, the colors begin to change. The reefs appear reddish brown just beneath the water's surface. White, sandy islands dot the seascape. Lush green islands covered in rain forests rise up from the sea. Shallow water surrounding the islands shines bright aquamarine. Below the surface, the Great Barrier Reef presents visitors with an eye-popping spectacle. Snorkelers and scuba divers can swim amid creatures of every color. Orange-and-white-striped lionfish. Purple crabs. Schools of pink anthia fish. Blue-and-black surgeonfish wriggling their bright-yellow tails to glide through the water. There are walls of coral in reds and pinks, giant clams with gaping multicolored mouths, and sea anemones with green tentacles. The Great Barrier Reef is not one giant coral reef. It is a system of three thousand individual reefs. More than 1,400 miles long, it is the largest coral-reef system in the world. It is longer than the distance between Seattle and San Diego! About 10 percent of the world's coral reefs are contained in the Great Barrier Reef. The Great Barrier Reef gets its name because it forms a sort of barrier , blocking the open ocean from the shore. It protects the mainland from storms and powerful ocean waves. There are more than six hundred islands in the Great Barrier Reef. If you include the islands in the Torres Strait (the body of water between Australia and Papua New Guinea), it's closer to one thousand! A few thousand years ago, some of these islands weren't islands at all. They were actually limestone hills on the mainland! How is this possible? It's because about a hundred thousand years ago, the world grew colder. Much of the water on the earth's surface became ice. Glaciers and ice caps grew larger. As more water in the oceans froze, the sea level dropped by more than four hundred feet. In Australia, coral reefs that had been underwater were now above the surface. Once the coral reefs were above water, they began to die and became hard. After many years, sun, wind, and rain turned these dead reefs into limestone hills. Mud and sediment washed up and over them. Eventually, plants and trees began to grow. Animals moved in. What once was a coral reef was now an all-new grassy landscape. Then, about eighteen thousand years ago, the earth's climate started to heat back up. Ice melted into the oceans. For the next twelve thousand years, the sea level rose about half an inch every year. Over time, the ocean swallowed up the land and covered up most of the limestone hills. Today, the tops of those old limestone hills are surrounded by water. They are among the islands we see in the Great Barrier Reef today. Many of these islands are surrounded by coral reefs. Today, on some islands there are popular tourist destinations. On others there are research centers, where people learn more about the Great Barrier Reef. But most of the islands remain pure wilderness, untouched by humans. Excerpted from Where Is the Great Barrier Reef? by Nico Medina All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
