Miracle Water is an item used by Mario during the events of Paper Mario. It is the last of three items that grant the plumber access to Cloudy Climb, the lair of Huff N. Puff.
Once the player refill Lily's pond with the Water Stone, she will reward Mario with the Miracle Water. However Mario will not be able to grow anything while the sun is still hidden by the effects of the Puff-Puff Machine.