The undersea world is very beautiful. Now more and more people want to 1 in the water to find the secret there. Scuba diving (水肺潜水) is a new sport today. It can take you into a wonderful undersea world.
If you are lucky, you will 2 find many strange animals in the sea. Some are as 3 as a school bus. Some are so tiny that you may not 4 them at all.
During the day, there is enough 5. Everything is blue and green. When fish swim nearby, you can catch them with your hands. When you have bottles of air on your back, you can stay in 6 water for a long time. However, you can't dive too deep. And you must be very 7 when you are in deep water, because something dangerous may happen unexpectedly.
The deep sea is not an easy place to live in. It's cold, and it's 8 too. The deeper it is, the less sunlight there is. At about 3,000 feet, there is no light at all.
Besides the cold and darkness, deep-sea animals face a third 9 —other animals. Animals eat! Many animals eat plants. However, some animals eat 10. This means these sea animals have two big jobs. They need to find animals as food, and they have to try not to become other animals' meal.
