What effect, if any, do water-creating spells have underwater?

There are a number of spells that produce their effects by conjuring and then manipulating large volumes of water, including Watery Sphere, Tidal Wave, and Tsunami. As far as I can tell, nothing stops someone from casting these spells underwater (assuming they are able to cast spells underwater, of course). However, it is not clear what effect would be produced by conjuring a mass of water in an area where there is already water. Would the spells have no effect? Would they have their normal effects? If so, what do those effects look like? What will happen when one of these spells is cast underwater?