How do I get over my Aquaphobia?

I'm dead scared of water especially the ocean and pools. I would rather get shot point blank in the head or beat up instead of stepping anywhere near an ocean or a pool. I don't know why but when I step foot on the shore or where I can see the ocean clearly it makes me feel like all freakish and all these thoughts start running crazy through my head like there's going to be a tsunami or I'm going to get touched by a fish or I'll be sucked down into the black part of the ocean. And when I step anywhere near a pool basically the same thing happens where I just think crazy things like there's a shark in the deep end of the pool and I start crying and just like freeze and then run crazily out of the water. By the way I'm 15 years old so I really want to get over this fear of water. I can shower and stuff but when I take a bath (or at least try to) I'm scared to step into the bathtub after I fill it up and that's why I shower. Also, if I look at pictures of the ocean or things like that it gets me scared too I can't even look at fish! :(