Hmmm no. The balloon (and the sphere) are pushed in the direction opposite to the sum of the forces applied to the surrounding fluid. Since the surface of the f

Hmmm no. The balloon (and the sphere) are pushed in the direction opposite to the sum of the forces applied to the surrounding fluid. Since the surface of the fluid is always orthogonal to those forces, there is no reason for a floating object to move in any direction but up with respect to the surface of the fluid. In other words, the fluid is not sloping, it's your head that's tilted :)