The Ice Arrow is one of the three magic arrows in several Zelda games, the others being the Fire Arrow and the Light Arrow.
In The Legend of Zelda: Ocarina of Time they are obtained by beating the Gerudo Training Grounds.
In Majora's Mask you obtain them in the Great Bay Temple after beating the miniboss Wart. In Wind Waker they are obtained on the Mother and Child Isles from the Fairy Queen.
When shot at an enemy the enemy will freeze solid. These arrows also freeze water.