With more and more people swimming at beaches every year, the problem of sharks (鲨鱼) takes on new importance. There are people who still insist that sharks never attack human beings unless they are bleeding or wounded, but this belief has not been clearly proved. In the past few years, on both the Atlantic and Pacific coasts, there have been cases of shark attacks which resulted in death. And just how many of the swimmers who have disappeared were victims of shark attacks will never be known. Clearly, these violent fish can be dangerous. Several species are known to attack human beings, and it is believed by some experts that certain sharks, once having tasted human blood, develop a taste for it.
The chances that one will come across a shark are small, but certain precautions should be taken by everyone. (A precaution is something you do in order to prevent something dangerous or unpleasant from happening.) Putting hands or legs over the side of a boat in warm waters is to be avoided. Swimming far out from beaches is inviting trouble. No swimmer should go great distances from shore alone, or go into the water when nobody else is about. Skin divers, particularly those who go deep down in the water or among rocks and ledges (暗礁) that serve as hiding places for sharks, are taking unnecessary risks.
If one is in a boat that is rubbed against by a shark, he should remember the creature is not trying to upset his boat; it is probably trying to rub off sea lice (海虱). A blow, especially on the nose, will drive it off. If a swimmer comes across a shark, he should swim away as quietly as possible, trying to avoid making it angry. He should also head for shore (岸) as quickly as possible.
