Throughout the game, there are a total of 20 happy masks that Link can collect. There are 3 transformation mask that allow him to assume the identity of a specific person, and change his appearnce, giving him special powers due to what form he has assumed.

DEKU SHRUB
The Deku Shrub is the smallest of Links alter egos. Deku Shrubs cannot swim, but they can hop across water for a certain amount of time, and are the only ones that can go through poison water. The Deku Shrubs main attack is the bubbles that you get from the Great Fairy, or a spin attack.

GORON
This mask contains the spirit of the Goron the Great Darmani. Gorons are extremely strong, and can break through large mounds of snow with a single punch. The Goron can also roll at high speeds, and with magic power spikes come out of their backs. Gorons cannot swim, so stay away from water.

ZORA
This mask lets Link assume the identity of the lead guitarist in the Zora Band, Mikau. Zora's are extremely agile swimmers, and can create a magic force field to fend off enemies. Mikau's fins can be used to slash and stab, or thrown like boomerangs.