How do you make being underwater LOOK like being underwater?

I have a problem.

If I jump into the water, I only jump through the surface, and then I’m in a big room with a blue roof. It doesnt look like being underwater. AT ALL…

I would like it if, when you jump into the water, it would look like being in some sort of “fog”, that looks like water (as realistic as possible ( I do not have unity pro ) ), and it would be really nice if the surface(the blue roof…) would be transparent as well.

At a bare minimum you could use camera effects (pro only). You’d turn them on when under water and back off when not. Check these out: