Use a bomb to stop the rolling Goron. Speak to him about the Dragon and the Gorons. He will ask you to rescue them and give you the Goron Tunic to aid you in your quest. The door to Darunia's room and the Goron shop will open automatically. Now enter Darunia's room and pull the statue at the back of the room to reveal a hidden entrance that leads to the Fire Temple. Make sure you put on your Goron Tunic or you won't be able to stay here very long because of the heat. Use the hookshot to get across to the bridge and Sheik will appear to teach you the Bolero of fire, then mysteriously disappear once again.
Time to enter the Fire Temple. Break the two pots for some magic refills if you need it then enter the door left side. BEWARE! A Like-Like will drop from the ceiling to attack you. Kill it and a small chest with a Hylian Shield will appear, useful if the Like-Like ate your shield. Exit and return to the main room, climb up the side of the stairs to avoid teh fire barrier now you will need fire arrows or Din's fire to light the two torches buried in the sides of the staircase. Then light the two unlit torches in the statues mouths to unlock the door on the left and enter it.
You will be greeted by Darunia who will explain about Gannondorf and Volvagia and askes you to save his people, he says he's going after the dragon himself and enters the boss room. Jump across the platforms to the right side and use Din's fire to light the two torches (one is hidden in a crate on the raised platform) and quickly use an arrow to light the torch across the room with either fire arrows or firing an arrow through the lit torch. If you take too long you will have to re-light the torches. Once all three are lit the gate will open, open the chest for a small key.
Return to the previous and enter the locked door on the lower right side of the room. BEWARE! There is a Keese waiting just inside the door to attack and there are also two Stalfos. The next room has 5 living tiles and an Iron Knuckles, so ready your shield! The next room contains a Mini Boss Flare Cragma, he can be easily defeated by dragging his weak inner body out with the hookshot and attacking with the hookshot and sword. When defeated a chest with the Megaton Hammer appears on the raised platform. Retrieve it and exit.
You should remember this room from before, its the room with the first trapped Goron, use the hammer to activate the rusted switch to free him, he'll only leave if you speak to him first and grab the dungeon map out of the chest. Now exit and use the hammer to remove the blocks blocking the door on the right. Now enter and head over to the platform on the right with two doors. Enter the bottom one and free the Goron. There is a Gold Skulltula on the back wall of the cage.