If you plunge deep into the sea, or even put your toes in the sea, you know it gets colder as you go down, and that's mostly because the deep waters that fill the abyss of the ocean come from the cold polar regions where the waters are dense.
如果你深潜入大海里， 或者只是让脚趾头碰到海水， 你就会知道越深处越寒冷， 这主要是因为， 填充海底沟壑的深海海水 是来自寒冷的极地地区， 而那里的水密度更大。