How does control water work in an underwater cave or underwater in general?

[Bob Fitzgerald]

Will control water work underwater or in an underwater cave with no air. If so what happens? It wouldn't create air and thus would a vacuum effect prevent it from working altogether or would it displace the water anyway? What application does control water have?

[Grey_Mage]

The water receds. If there was no air, there is still no air. If there was, some air remains.

Better answer: Whatever the GM desires. Magic and physics shouldn't interact. Otherwise Grease spells become flammable, electricity spells become AOEs in water and all other kind of table variation rulings will happen. So it just happens. After all it's magic.