So I have it set up in my game that when you walk around a sound plays while walking on the ground and the sound changes when you walk over water/puddle. The problem I have is that the sound continues to play when I am in the water swimming around. I think I have to set a variable to is swimming then don’t play the sound while in the physics volume. However I’m not sure how to do that. Any help is greatly appreciated!!
you are on the right track 
i would create a music control blueprint, add all your music as references inside, then when your player “is swimming” fade the volume in and out. (i wouldn’t start and stop it or you might have cases when the player just bobs up and down in the water thus restarting the tracks)