Is it natural to say, "She is floating in the water" or "She is floating on the water", when two-thirds of her body is below the water surface?
The dictionaries say "There was something floating in the river." (source) and
"The boat floated on the calm sea." (source)
Best Answer
"In" is fine in this context, "on" would tend to suggest that the object is mostly out of the water. But you could hear "on" being used in similar situations too. There is a lot of fuzziness, and both "in" or "on" are quite acceptable in many situations.
It would be more likely to say "floating in the pool" rather than "in the water", as "water" is assumed. In this case "in" is more likely, unless you specify "surface" as in "there was a stick floating on the surface of the pool".