Minecraft wiki entry for Player_versus_Player, associated text: If you are in water, always go under your opponent! Be sure not to drown, though. This also applies when you're trying to hit someone and they're up on a mountain! That way, unless they are cheating, you will easily be able to knock them up on the mountain, plus your hits will make them unable to sprint, due to the fact that they are hit against a block. In water fights, you should always keep lily pads and jump off one while looking down and holding right click, so the lily pad will be placed right when you are about to hit the water, and so you will basically be able to walk on water. This works if you want to run, or if your opponent is running, because in water, your speed is so low and the knockback is so high that you will only be able to get 2-4 hits on them before they are 10 blocks away. Note that ping affects this.