Classic boating cork keyring designed to keep your keys afloat.
Cork ball keyrings, the simplest and still the most favoured way to keep your keys afloat if they fall overboard.
A large buoyant cork ball on a cord with a split ring to attach your keys. Not quite as small as some modern pocket sized floating keyring designs; but why hide that you own a boat! Best of all, it is completely reusable too, unlike some of the more fancy keyring gadgets.
It is important to check your keys will be supported before actual use.