That’s a good question and has required a bit of thought on my part, always a good thing. The key thing about my acoustic levitator is that sound waves are pressure waves, so they are dependant on there being a medium (air in my case) for the sound to travel through. It would work equally well in water, perhaps even better.
There are other types of levitation , most notably magnetic. The drawback with this is that you need the thing that’s being levitated to be magnetic. Fortunately, anything with water in is as water is very very weakly magnetic. This is why you can do things like levitating frogs: