This sea-green crystal always feels moist to the touch.

A crystal of aquatic action aids the wearer while underwater.
Any armor bearing this augment crystal does not impose an armor check penalty on your Swim checks, and you also gain a Swim speed equal to one-half your land speed (round down to the next 5-foot increment).

Prerequisites: Craft Magic Arms and Armor, freedom of movement, water breathing.
Cost to Create: 500 gp, 40 XP, 1 day.