The seawater out there is a freezing minus four degrees, but these swimmers are splashing around at a balmy 19.

里海水有零下 4 度，是结冰温度，但些游泳者却在温暖 19 度海水中戏。

Such low energy content in our bodies just isn't worth the effort for a shark, and that's why many swimmers splash in waters every single day that are infested with sharks, and are none the wiser for it.

我们身体中如此低能量含量对于鲨鱼来说是不值，就是为什么许多游泳者每天都在鲨鱼出没水域中戏， 并且对此一无所知。