Buoyancy

Transmutation
Level: Artificer * 2, Bard * 2, Shaman * 2, Sorcerer */Wizard * 2, Warlock * 2
Components: V
Casting Time: 1 Immediate Action
Range: close (25 ft. + 5 ft./2 levels)
Target: one Medium or smaller object or creature/level, no two of which can be more than 20 ft. apart
Duration: up to 1 round/level (see text)
Saving Throw: Will negates (harmless) or Will negates (object)
Spell Resistance: yes (object)
  The affected targets become incredibly buoyant, floating naturally on any water at least 1 foot deep.
  An affected creature that deliberately tries to submerge must succeed at a DC 20 Swim check every round to stay underwater. If a target spends at least 1 round on dry land, the spell ends for that creature only.