Removes the penalty when breaking blocks while underwater and flying.
From the minecraft wiki:
"If the player's head is underwater and they are not wearing a helmet with the Aqua Affinity enchantment, breaking a block takes 5 times as long. If the player's feet are not touching the ground, an additional 5x penalty is added; this causes players floating in water to break blocks 25x slower than if they had been standing on land."This mod removes that, meaning when underwater and flying the block breaking speed will be the same when on a surface.