The Penguin Suit as it appears in New Super Mario Bros. Wii
The Penguin suit is a rather recent power up that just apeared in New Super Mario Bros. Wii. When Mario uses the penguin suit he can swim faster and with better control under water. It also allows him to walk on ice without slipping, which can be a great benefit.
The Penguin Suit has one similar effect to the Ice Flower: Mario can still throw Ice Balls by pressing the 1 Button on the Wii Mote. Hold the 1 Button down while running and press Down on the D-Pad and Mario will slide, breaking any Bricks that are in his path. The effect works greater on ice, where Mario can slide for a longer period of time. Mario can still jump while sliding, which is helpful for finding some of the "hidden" stuff in the game.