33. A Deadly Current it is a pity that every summer a few people drown at the beach. In some cases， these people were good swimmers. So how did it happen？ Riptide！ Riptide is a strong underwater current. It moves quickly away from shore and out to sea. It appears suddenly and pulls its victim under and far off shore. Therefore， people should make it a rule never to swim too far out from the beach. If you find yourself in a riptide， don t panic. And by no means should you try to go against the tide and swim back to shore. You ll tire yourself out and probably drown. Instead， swim parallel to the beach. A riptide is very narrow. So just a few strokes in the right direction and you ll be out of danger.