Blue Flame

Blue Fire an item in and a type of fire.

Ocarina of Time
In, Blue Fire can be found in the Ice Cavern and Ganon's Castle. It can also be bought at the Medicine Shop for 300 Rupees. In, it can also be found in the Gerudo's Training Ground.

Blue Fire is used to melt Red Ice. Link must first scoop it from a pedestal by using an empty Bottle or buying it from the Medicine Shop. Blue Fire is required to progress through the Ice Cavern and obtain the Iron Boots. It is also needed to get the Zora Tunic by melting the Red Ice in which King Zora is encased. Alternatively, Link can melt the Red Ice blocking the entrance to the Zora Shop in order to buy the tunic. Blue Fire can also be used to obtain a Piece of Heart encased in Red Ice within the Ice Cavern.

When flying through Blue Fire, Keese will become Ice Keese.

Breath of the Wild
In, Blue Fire is a type of Fire that never burns out while in a Torch. Certain Torches can only be lit with Blue Fire, such as inside the Divine Beast Vah Rudania, within Ancient Shrines and outside of both Ancient Tech Labs. Link must bring Blue Fire to both Ancient Tech Lab from a nearby Blue Fire furnace in order to activate certain features of the Tech Lab. Link must use a wooden weapon, such as a Torch or a Tree Branch, to transport Blue Fire. At the Hateno Ancient Tech Lab, this will allow Link to upgrade his Sheikah Slate. At the Akkala Ancient Tech Lab, this will allow Link to exchange ancient Materials for many types of ancient Armor and equipment. If Blue Fire is used to set flammable objects on fire, it will behave the same way as normal Fire.

Trivia

 * Blue Fire can destroy bombable walls.
 * features a similar object which "burns" the Boomerang and can be used to freeze water or transform Keese into Ice Keese. This fire cannot be contained or transported.