Video of an Infinite 1-Ups Technique in World 4-1
Another location where this can happen is in World 4-1. Near the beginning of the stage, there is a patch of water. There is a Koopa Troopa in front of the water. Kick the Koopa into the narrowest portion of water on the far left so it bounces quickly back away and towards the screen. Try to jump on the Koopa near the edge where it turns around. If you land on it in the right place, Mario will bounce, getting a life every time he lands after the first few hits. No presses of JUMP are needed to keep Mario jumping on the shell. It may take a few tries before this works.
Added by: piking Jul 6th 2012, ID#382