Airy Water

This spell turns normal water (or watery solutions) into a frothy substance that is as breathable as air. Both air-breathing and water-breathing creatures within the area can breathe normally. Moving through airy water is easier than moving through normal water. Swimmers make a DC 10 Swim check once per round; they swim at their normal speed on a success, or half their normal speed on a failure. Creatures with a swim speed can simply use their swim speed without penalty. Creatures can instead use their land speed to move along the bottom at their normal speed. Creatures walking on the bottom do not pay any movement penalty for walking on sand, stone, or pebble seafloor and only pay 2 squares of movement per square of muck or mud entered (see Marine Dungeon Terrain on page 21). Finally, airy water negates underwater combat penalties for all melee attacks, although ranged attacks still take the normal underwater penalty. The spell does not filter or purify solid particles, so casting airy water on very turbid liquids, for example, would produce an area filled with dust or smoke (and impose similar penalties). Material Component: A small handful of alkaline salts.
 

You transmute the water within a 20-foot radius around you into a frothy, breathable medium. For the duration, this area moves with you. Creatures inside the area can breathe normally, regardless of whether they breathe air or water.   Movement within the airy water is eased:

• Creatures without a Swim speed can swim at their normal walking speed with a successful DC 10 Strength (Athletics) check made at the start of each of their turns; on a failure, they treat the water as difficult terrain as normal.
• Creatures may walk along the bottom of the airy water at their full walking speed, assuming it is contacting a solid surface, ignoring difficult terrain from sand, stone, or pebbles, through muck or mud still acts as normal.

Additionally, melee attacks made within the airy water suffer no penalties for underwater combat, though ranged attacks still follow the normal underwater rules.   This spell does not remove particulates or impurities; casting Airy Water in turbid or polluted liquids fills the area with clouds of debris or smoke-like material, imposing visibility penalties as appropriate.   At Higher Levels. When you cast this spell using a higher level spell slot, increase the radius of the airy water by 10 feet for each slot level above its base level.