Infernal Dinosaur King Dodongo is the boss in Dodongo's Cavern, which is the second dungeon in what is arguably the greatest videogame ever created, The Legend of Zelda: Ocarina of Time. Dodongo's Cavern is where a race of creatures known as the Gorons get all their delicious juicy rocks from. King Dodongo was placed in the cavern by the principle bad guy in the game, Ganondorf. He did this to cut off the Gorons' source of food, because he was angry that Darunia, the leader of the Gorons, would not give him the Goron Ruby. To beat the game, you (as the young protagonist Link) must enter the cavern and defeat King Dodongo.
Dodongo is a large, brown, reptilian quadruped with an invitingly large, pink mouth. He stomps about at a relatively low pace but can also curl up and roll. He bears a resemblance to the smaller, green Dodongos that you met earlier in the dungeon.
The arena is smaller than most. It is square, with a large round lava pit in the middle. If you step in the lava, you will not die instantly, but you will take more damage the longer you stay in it. Around the edge of the arena is a wide path which you and King Dodongo stay on. In each of the four corners of the arena is a bomb plant. There are no incidental pots which might contain hearts - you're on your own this time, but this boss is relatively easy so there should be no problem.
Dodongo is a wide beastie, and takes up almost the entire width of the safe path around the edge of the arena. Normally, he will stomp slowly towards you. If you get within range, he will open his mouth and inhale deeply; then he breathes a VERY big and VERY long blast of flame at you. This flame can take up as much as a quarter of the length of the safe path - you may retire to a distance you think is safe, but still get hit. The flame also does you a lot of damage, and if you are still using the Deku Shield at this point, then it will get burnt to a crisp.
Periodically, and often after fire blasts or after being damaged, Dodongo will curl up into a ball and roll along the path after you, ricocheting around corners. After this he will usually end up on the other side of the arena, then curl up again and come back around after you. To avoid this, stand on the very inner edge of the path, right near the lava, and he should roll straight past you.
How to beat King Dodongo
You will need: Bombs, Kokiri Sword
Dodongo is pretty much invulnerable to any kind of attack most of the time, but sticking to the traditional element of Zelda games (to beat the boss of a dungeon, you have to use the major item you picked up in that dungeon - in this case, the Bomb Bag) he is vulnerable to bomb attack. Wait until he opens his mouth to breathe fire at you, then whip out a bomb and run forwards to throw it in his mouth. He will swallow the bomb, which will explode in his stomach, stunning him. As with all bosses in this game, he must be stunned before he can be damaged, so now run forward with your sword out, Z-target him and do a jumping attack (this does twice the damage of a normal attack). After this, Dodongo always does his rolling attack, so stand aside.
The mouth is a huge and obvious target and is almost impossible to miss, unless you accidentally set the bomb down instead of throwing it. If you run out of bombs, all is not lost - you can use the bomb flowers instead, although this will require some better timing. Repeat the stun-then-attack pattern until Dodongo bites the dust. He will roll into the lava and die. Don't forget to collect the Heart Container before you enter the blue warp to the exit of the cavern, where you will receive the Goron Ruby as a reward from Darunia. Next stop - Zora's Domain...
How to beat King Dodongo - speed strategy
If you are attempting to complete OoT at high speed, then it is best that you use a fast rather than a conservative method to beat the bosses. For this method you will instead use Deku Sticks. These are the most powerful weapons available to you as Young Link; a jumping attack, if on target, will do well over twice as much damage to King Dodongo than your Kokiri Sword ever could. However it will also break the stick. Therefore you should have at least three on hand for this battle.
Same basic strategy: stand right in front of King Dodongo's mouth, whip out your first bomb when he opens his mouth and lob it in. Get out a Deku Stick and jump-attack him using Z-targeting. Stand aside while he does his roll attack; then repeat. Two (yes - two) jumping Deku Stick attacks should see him off.
This was the first boss from The Legend of Zelda: Ocarina of Time.
Previous boss: Queen Gohma.
Next boss: Barinade.