By use of this spell, the
mage can allow normally non-buoyant objects to float upon
a layer of small crystal bubbles filled with air.  Up to 100
pounds of matter per level of the caster can be made to
float, including gold, lead stone, or a living creature.  An
object that has sunk can be raised to the surface if the
object is within the spell's range.

MC: Small cork and a pinch of bromine salt.