Subterranean Lava Dragon: Volvagia is the fifth boss in The Legend of Zelda: Ocarina of Time.
Speed strategy
You can dodge all of Volvagia's attacks by hanging off the edge of the platform you're on. For the circling/flaming attack, if Volvagia comes out and doesn't see you, he'll dive right back into the next hole, so stay as close to the edge of the platform as possible for this attack, so that they last as little time as necessary.
ALWAYS do a jumping attack with your Master Sword or the Megaton Hammer - you'll need four of these if I remember rightly - as you have ample time to do so and any time lost will result in another dull and lengthy rock or circle/flame attack.
Stand on the dragon's head to collect the Heart Piece as expediently as possible.
On an optimum run it takes just under two minutes from entry to exit. See Minimal runs of OoT for information on beating Volvagia without the Goron Tunic.