1. In some places swimmers may encounter strong undertows or ocean currents. 在一些地方游泳者可能遇到强势的暗流或者洋流。
2. Unless this is flooding the shore, all this water is somehow returning to the ocean. There are a couple of ways it can do this: undertows and riptides. 除非淹没海岸,所有的水终将以某种方式回到大海之中——潜流或者激流。