Fog
A billowing Blue Fog can be found in certain areas of the Earth Temple. If Link comes into contact with it, he will become "cursed", meaning that none of his items work, including his sword. While affected, Link is surrounded by a concentrated smog, his body flashes purple, and he acts disoriented or weakened. This is markedly similar to being cursed by a Blue Bubble. The curse will not be lifted unless he gets out of the fog or finds a beam of light to take refuge under.
To get through the foggy areas safely, Link can use the Deku Leaf to blow the fog away from a small area at a time, and if he shines light at it with his Mirror Shield, the part of the fog exposed to the light will dissipate. Medli can also use the face of her lyre in the same fashion. The pair will often have to work together to travel through, or over, the fog unhindered.
This fog also has similarities with the Dark Fog from Twilight Princess.