Cast spells while swimming?

[Evil the Cat]

I've been trying to find specific rules for trying to cast a spell while swimming. other than fire spells being directly affected, I'm not sure exactly how this would work.Does anybody know if/where there are specific rules for casting a spell while swimming. I ruled that using somatic components while swimming wasn't possible, but I'm not certain if this is the best way to go.

[Keld Denar]

As long as your head is above water, look under Concentration in your PHB. Calm water would probably be vigorous motion, while stormy water would be violent motion, making the DCs 10 and 15 + spell level apiece.

If you were actually under water, then unless you had some form of ability to breath water (Alter Self into a Triton, cast Water Breathing, etc) then you couldn't cast any spells with Verbal components since you couldn't speak under water.

Hope this helps.

[Kurald Galain]

I'm not sure if there are any rules on the topic (2E has them in the Complete Wizard's, but that's probably not what you're looking for).
However, I would rule that casting anything with somatic components is not possible while swimming (or I'd impose a draconian concentration check). If the plot would require the PCs to frequently attempt casting while swimming, I'd let them search for a magical item that compensates.

[Ascension]

Cloak of the Manta Ray should take care of it... if you can use your weapons without penalty you should also be able to use spells with somatic components without penalty.