The ocean floor off the west coast is too sandy, and the bedrock too loose for coral to attach itself. The east coast, on the other hand, possesses ideal conditions for coral growth-it is in the pathway of the Kuroshio Current, the water quality is good, and the temperature perfect-but the ocean floor tapers too precipitously and some of the currents are very forceful, making coral growth there tenuous.
西部因為是沙岸，底質鬆軟，珊瑚不容易附著，東岸雖然也有黑潮經過而且水質清澈、溫度適宜，原本是珊瑚生長的好環境，但因為海底坡度陡峭，有些地區海流強勁，珊瑚生長的情形不一。