The Flippers are one of the items in Cadence of Hyrule that gate your progression in the game. You’ll need them if you want to cross waters that are too deep to wade through. The Prince of Zora has the flippers, but unfortunately he is under the spell of some ghosts in a cave. To get the flippers you’re going to have solve a small puzzle.
When you enter this cave you will see numerous ghosts and the prince sleeping at the top of the room . One of these ghosts will respond to you if you walk up to them, and this is the one that you need to hit with a bomb to start a small boss fight that will wake the prince.
Once the prince is awake he will give you the Flippers as a reward. Zora’s Flippers are a passive item that don’t need to be equipped to be used. Once you get them you simply be able to access areas that were previously not available because there was deep water in the way.
The Flippers will allow you to access the Frozen Grotto area which is the home of yet another boss fight, one of the four needed to beat the game.