Instructions
Load "Minecraft" and enter the game world where you need to build an elevator.
Dig a small trench one block deep into the ground floor of the elevator.
Place water at the top of the elevator shaft so that it pours down into the trench. You will need to fill up every space between the top and bottom of the shaft with water.
Place a boat into the pool of water at the bottom and jump in. Push into the waterfall and you will begin to rise.
Travel down the elevator by jumping down into the pool of water. You will take not fall damage if it the water is deep enough.