这些人是擅长游泳的，他们失去生命的原因是因为在水下面看不见的魔鬼。

The people who died were good at swimming, the reason they got killed was the invisible demon under the seawater.

youdao

所有的海龟都得把头伸出水面呼吸，但是，很奇怪，有些水塘乌龟只有头在水下面时，才吞得下东西。

All turtles have to put their heads out of water to breathe, but strangely, some pond turtles cannot swallow unless their heads are under the water.

youdao

周围一个人也看不见，在他的下面，在水下，游泳者们的模糊的影子也消失了。

There was no one visible; under him, in the water, the dim shapes of the swimmers had disappeared.

youdao