翻译Sea.为什么要大写第一个字母

Ocean water is heated by the sun near the equator and drawn by the rotation of the earth toward the poles,where it cools and drops toward the ocean floor and starts its journey back toward the equator.The differential between the two currents is 35 degrees to 45 degrees Fahrenheit and to use it the scientists must find the places where they run near land and are not too far away from each other.One area that meets these requirements is the Caribbean Sea.
海水在赤道附近被太阳加热后因为地球的自转被甩向两极，
在两极，海水冷却下来下沉到海底并开始返回赤道的旅程。两种洋流的温差有华氏35到45度，要对此加以利用的话科学家必须要找到他们流近陆地的地方并且两者不能相隔太远，达到这些要求的地区之一是加勒比海。

Sea大写是特指，

因为是专有名词

Caribbean Sea 是一个专有名词 专指加勒比海。
因此 根据英语的语法 应当大写