Let Penguins help flying players in the water

First, you need to obtain a Penguin feather--nonviolently of course. Trading for them can be one way; another way is when they despawn naturally. When mobs despawn, they just disappear. But if a Penguin drops a feather when it despawns, that will make it unique in one way already.

Second, the use of the Penguin feather is to help you glide into and out of the water while flying with an elytra. Normally going into water will stop your flight cold, but if you have a Penguin feather anywhere on your hotbar, the Penguin Feather gets consumed and you can fly through and back up out of the water without losing any momentum. Of course, each time you go in the water it uses up a Penguin Feather in your hotbar until you have none left--and then it's flight canceled as per normal.