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 Red Candle is an upgrade to the Blue Candle that can be obtained in Level 7 of the First Quest and the Second Quest. When used, the Red 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. While the Blue Candle can only be used once in a given area, the Red Candle is able to emit an unlimited amount of Fires in an area.[3]