Ring of The Octopus (3.5e Equipment)
From D&D Wiki
Ring of The Octopus: This ring is shaped like an octopus, its tentacles gripping the wearer’s finger. When underwater, the wearer gains a +10 competence bonus on Escape Artist checks. The wearer can also breath underwater and use the run action while swimming, provided he swims in a straight line. The wearer can always choose to take 10 on Swim checks, even if distracted or endangered. The ring’s wearer cannot breath air and begins to drown if the ring is worn out of water.
Moderate transmutation;CL 7; Forge Ring, polymorph, water breathing; Market Price: 26,950gp