Bailer's Boots
Boots habitually worn by a sailor for at least a year and a day (+5 gp per tooth)
These lightweight boots are watertight and keep your feet dry no matter what. They have small sailing ships etched into their ruddy surface and are decorated with several shark teeth along the collar.
A newly made pair typically has six teeth, but found pairs will have 1d4 + 2. As a reaction, you can remove a shark tooth to cast alter self with the amphibian option. Casting the spell in this way does not require concentration , but the changes remain in effect for the full hour duration and cannot be changed except with dispel magic or similar effects. When the last tooth is removed the boots become mundane items that are still surprisingly waterproof.