The airy water spell turns normal liquid, such as water or water-based solutions, into a less dense, breathable substance.
Thus, if the wizard wanted to enter an underwater place, he would step into the water, cast the spell and sink downward in a globe of bubbling water. He and any companions in the spells area of effect can move freely and breathe just as if the bubbling water were air. The globe is centered on and moves with the caster.
Water-breathing creatures avoid a sphere (or hemisphere) of airy water, although intelligent ones can enter it if they are able to move by means other than swimming. No water-breathers can breathe in an area affected by this spell.
There is only one word that needs to be spoken to actuate the magic, thus it can be cast underwater. The spell does not filter or remove solid particles of matter.
The material component of the spell is a small handful of alkaline or bromine salts.