Sea Steed

Transmutation (Polymorph)
Level: Druid * 2, Hunter * 2, Paladin * 2, Ranger * 2
Components: V, S, DF
Casting Time: 1 Standard Action
Range: touch
Target: a creature you are mounted upon
Duration: 10 minutes/level (D)
Saving Throw: Will negates (harmless)
Spell Resistance: yes (harmless)
  The target adapts to life in the water, gaining piscine scales that cover its body and growing fins in place of feet. It gains the aquatic subtype, the amphibious quality, and a swim speed equal to its base speed before it came under the effect of this spell. While under the effects of this spell, the target's base speed is reduced by 10 feet (minimum 10 feet).