WorldBuoyancy

WorldBuoyancy is a mod which adds liquid-related functionality.

• The “inventoryBuoyancy” feature makes wooden item stacks float up the slots of the inventory GUI while you’re submerged in water. For instance, if you have a wooden plank in your hotbar and jump into water, the plank will be moved to the upper areas of your inventory. Non-wooden item stacks can block the wooden item stacks from moving up. If Better With Mods is installed, it will float the items BWM considers as “floating” instead. That’s literally what it does, no less, no more.
• The “cannotDisplaceLiquids” feature makes it only possible to remove fluid via a bucket or other container; displacing it with a block will simply make it respawn nearby.

I mean, why not? (It’s not meant to be entirely serious.)