Question

why is pacfic ocean so cold

Answer 1

Answer:

With the top level of the ocean pushed away, space is available for deeper, colder waters to rise to the surface. This is a process known as “upwelling” (here's an animation describing what it is), and is the reason that the Pacific coast is known for its cold waters.

Answer 2

Because, ocean water rotates clockwise, coldy salty water is dense and sinks in bottom water gets colder with depth.