From Pathfinder Lost Omens The Grand Bazaar, which isn't enabled.

Waverider Barding

ITEM 5

COMPANION INVESTED PRIMAL

Price 130 gp

Bulk L

Category light barding

AC Bonus +1

Dex Cap +5

Strength +3

Check Penalty −1

Speed Penalty −5 ft.

This light barding is covered in wavelike patterns. The barding adjusts to fit your animal companion regardless of its shape.

Activate Interact

Frequency once per day

Effect You trace a finger along the wave patterns on the barding, granting your companion a swim Speed of 30 feet for 10 minutes. If your companion already had a swim Speed, it gains a +10-foot item bonus to its swim Speed for 10 minutes instead. Even if the companion doesn't have the mount special ability, it can still Swim while being ridden.

Pathfinder Lost Omens The Grand BazaarOGL