Aqua Affinity

Aqua Affinity is a rare armor enchantment in Minecraft 1.21. Aqua Affinity removes the heavy mining-speed penalty you normally suffer while your head is underwater, letting you break blocks at full land speed beneath the surface.

There is only one level to it, so nothing needs upgrading — the instant it goes on your helmet you have the whole effect (Removes the 5x mining speed penalty while underwater).

Aqua Affinity exists at a single level only, so there is no scaling curve to climb — applying it to your helmet hands you the complete effect in one step, with no Aqua Affinity II to chase.

There is one level with no scaling. Without it, mining underwater takes roughly five times as long; with it, the penalty for being submerged disappears entirely, which is transformative for any underwater excavation.

Aqua Affinity fits exactly one item — the helmet — and nothing else will accept it, so it is a dedicated helmet enchantment through and through.

Aqua Affinity has no exclusivity conflicts at all, so you can layer it onto a helmet alongside every other enchantment that helmet accepts without having to give anything up.

Aqua Affinity can be rolled directly at an enchanting table, where reaching its top level of I on a helmet generally wants a fully bookshelf-powered table at roughly level 6. When the enchanting table refuses to offer Aqua Affinity, the same enchantment is available as a book from loot chest and villager trading for anvil application.

Its selection weight of 2 makes Aqua Affinity a rare roll: it surfaces only now and then on a helmet, so you may need to re-roll several times or simply trade a villager for the book.