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Shoulders-Up Nudity could apply I suppose, the page image does have something close. The logic being the character have the water always up to the shoulders (female) or waist (male) to conceal their nudity.
Sexy Silhouette if the body under the water is just seen as a silhouette.
Shoulders-Up Nudity is the one you want
Scenery Censor sets in if there are additional obstructions used in combination with the water, and Censor Shadow if they play with the lighting as well
Edited by Scorpion451

In numerous anime, the surface of water is used as an effective censor for nudity. This is also sometimes used to tone down nudity in live action film, e.g. the brief swimming scene from Ohlahoma!.
In reality, the tendency of water to reflect and refract can significantly conceal things below the water line, hence the existence of live action examples. In anime (at least, the ones that I usually watch where fanservice is kept low key), this is usually exaggerated by some combination of art style, lighting, and viewpoint, rendering the portion of the character underwater a faint silhouette or entirely invisible, probably for some combination of better censorship and easier animation.
While we frequently see a ring of froth immediately around an animated character at the water line, this isn't soap or bubbles (I am not aware of any examples in a western bath, where soap bubbles are usually used - in live action, it's a pond; in anime, it's an onsen or ofuro; in all cases, people are soaking or swimming, not washing) and in any case isn't necessarily effectively placed to itself conceal (usually) nipples. Therefore, this is not censor suds. Similarly, steam is not typically present, so it is not censor steam.
So what is it?