The material below is Open Game Content from a 3PP Source
Pearl of the Sirines
Aura moderate abjuration and transmutation; CL 8th
Slot none; Price 15,300 gp; Weight —
This pearl is worth at least 1,000 gp for its beauty alone, yet if it is clasped firmly in hand or held to the breast while the possessor attempts actions related to the pearl's powers, she understands and is able to employ the item.
The pearl enables its possessor to breathe in water as if she were in clean, fresh air. Her swim speed is 60 feet, and she can cast spells and act underwater without hindrance.
Requirements Craft Wondrous Item, freedom of movement, water breathing; Cost 8,150 gp