In One Piece, is there a Devil Fruit that makes you a great swimmer? It seems impossible since eating a Devil Fruit makes you unable to swim. Does the series ever address this?
There is actually a canon answer to this. The Sui-Sui No Mi (official english name is Swim-Swim fruit) is a Paramecia Fruit eaten by Senior Pink.
As the ocean is inaccessible to Devil Fruit users, the Swim-Swim Fruit makes you an excellent swimmer... through anything else including solid material (except seastone).
Unless Oda decides to create one, no devil fruit will exist which is a loophole to allow the user to swim through water.