Minecraft wiki entry for Defeating_the_ender_dragon, associated text: Because falling into the void kills you and destroys your gear, you should stay as close to the center of the island as possible, or at least inside the circle of towers. If you get knocked off, you should immediately throw an ender pearl back up. If you are quick enough, and have aimed your shot correctly, it is possible to teleport out of the void and back onto the surface.