Some of the rooms inside of the labyrinths are really dark. So use these to brighten them up. Blue candles are good for one screen only, but the red ones can light up rooms for several screens.
The Blue Candle can be purchased from certain Shops for 60 Rupees in both the First Quest and the Second Quest. When used, the Blue Candle will emit a temporary red Fire to a short distance in front of Link, which can illuminate dark rooms within Dungeons and damage certain enemies.[2] Link can be hurt by the Fire as well. It can also be used to burn certain Trees throughout the Overworld, which will reveal hidden staircases that often lead to Caves. Burning a certain Tree will reveal a staircase leading to Level 8 of the First Quest or Level 7 of the Second Quest. The Blue Candle can only be used once in a given area, so Link must walk to another screen if he wishes to use it again.[3] Link can replace the Blue Candle by obtaining the Red Candle in Level-7 of both Quests. The Red Candle functions identically to the Blue Candle, except it is able to emit an unlimited amount of Fires in an area.[3]