Up to 50 meters below the surface, tropical  and temperate waters house another unusual environment: a meadow grown entirely underwater.

在海面以下 50 米处，热带和温带水域拥有另一种不寻常的环境：完全生长在水下的草地。

This is the genesis of ocean surface currents  which carry warm tropical water up to temperate latitudes, or cool temperate waters down to the  tropics.

这就是海洋表面洋流的起源，它将温暖的热带海水带到温带地区，或将凉爽的温带海水带到热带地区。