Well, however it works, there surely is a force that defines the direction things buoy in.  They don't just go willy-nilly in direction when You hold them out and let go.  I call it "gravity."

I give highest probability that there is positive and negative "gravity," both very strong, but they almost cancel one another out.  And that they are related to the electromagnetic forces - a third dimension, if You will.  Not mass-related, per se.