In that case take an insulin syringe, then stick it in the top along the back.
Inject some air, to make a air bubble, when you pull the syringe out put a drop of super glue in the hole, and hold it for a few second for the hole to seal.

Maybe that will make it float.

You can get syringes at any drug store or walmart.
Or where you get animal medicines like Tractor Supply.