Inaccurate?

Steed of the Seas

(Stormwrack)

Transmutation
Level: Paladin 2,
Components: V, S, DF,
Casting Time: 1 standard action
Range: Touch
Target: Your mount
Duration: 2 hours/level (D)
Saving Throw: None
Spell Resistance: Yes

Paladins are understandably loathe to enter into the water depths without their loyal steeds to assist them.
With this spell, you imbue your mount with the ability to enter the water without harm by granting it the aquatic subtype.
Additionally, the mount gains a swim speed equal to half its normal speed.
A mount under the effects of this spell is able to breathe water; in fact, it is amphibious and thus subject to no ill effect in or out of the water.