Skin-diving( 潜水 )is a new sport today. This sport takes you to a new wonderful world. It is like a visit to the moon! When you are under the water, it is easy for you to climb big rocks ( 岩石 ),because you are no longer( 不再 ) heavy. Here, under the water, everything is blue and green. During the day, there is enough light. When fish swim nearby, you can catch them with your hands. When you have a tank ( 罐 )of air on your back, you can stay in deep ( 深 )water for a long time. But you must be careful when you dive in deep water. To catch fish is one of the most interesting parts of this sport. Besides ( 除此以外 ), there are more uses for skin-diving. You can clean ships without taking them out of the water. You can get many things from the deep water. Now you see the skin-diving is useful and interesting.