Touch of the Sea

Drinking this potion will cause webs to grow
between the fingers and feet to transform into flippers, granting a swim speed of 30 feet
along with the standard +8 bonus on Swim checks
and the ability to take 10 even if distracted or endangered. You can also use the run action while swimming, provided you swim in a straight line.
Any boots or gloves worn will meld into the form (magic items with a continuous effect continue to function). This potion does not grant the target
any ability to breath