在澳大利亚的东北海域有一条南北连绵2000余公里平均宽约65公里的浅礁。大堡礁低潮时,水上面积约8万平方公里,人可以在上面行走,涨潮时,礁石被水掩盖,不见踪影,这时,如果从空中俯视,会看见海中有一条白色的浪带,那是 In Australia's northeastern waters there is a shallow reef with an average width of 65 kilometers, about 2,000 kilometers north-south. When the Great Barrier Reef at low tide, the water area of ​​about 80,000 square kilometers, people can walk on it, high tide, the rocks covered by water, disappeared, then, if looking down from the sky, you will see the sea has a white belt, that is