Minecraft wiki entry for Mining, associated text: Second, stand in the pit between the water and the sign, and start digging below the water. When you reach the limit of your reach, start digging on the other side (below the sign). Remember to always keep the hole at least one block deeper below the water than below the sign, so that the water does not flow sideways and push you away from the optimal spot. You can stand slightly towards the side with air, while still touching the water, so that you can breathe.