Super Mario World/Yellow Switch Palace

The Yellow Switch Palace is the first of the four switch palaces in Super Mario World, located on Kappa Mountain.

Walkthrough

 * You'll see a lone P-Switch standing there. Step on it to fill the entire room with coins. Since you can enter this level only once, use this opportunity to get as many coins, and thus 1-ups, as possible. Once you're done, enter the pipe at the right side to get to the second area.
 * In the second part, simply run forward and step on the huge yellow switch. This will activate all the yellow blocks in the game. You'll also be given the opportunity to save the game here.