The first boss you will have to fight against in The Wind Waker is Gohma, the giant Magtail queen situated in the centre of Dragon Roost Cavern. The island's protector, the sky spirit Valoo, has become distracted by the creature hurting him from below, which have made him become rageous and causes confusion and panic among the Rito. Medli and Link enters the cavern to find out what is troubling the spirit.
As soon as you enter the bossroom and the animation is over, you can perform a sidehop to save a few frames triggering the cut scene. Link will always be placed at the same spot after the cut scene so the way you trigger it does not effect the outcome.
The first phase of this battle is based on destroying the armor which is protecting Gohma from getting hurt. There is only one way of doing this and that is making the bedrock from the ceiling, encircling Valoo’s tail, fall down on top of her until it breaks. For this, you will need the grappling hook.
Directly after the cut scene of Gohma introducing herself is over, you can take out your grappling hook and aim for the tail in the ceiling above her. The amount of time it takes for Gohma to make her first seizure is random, but you are always able to get a quick aim, toss it and get over before she makes her first move. To expand the time you get, and to simplify the aim, you can do a quick backflip before aiming the grappling hook.
As soon as the hook has attached itself to the tail Link begins to swing. Now it is all about releasing the hook and get over. As soon as you have landed on the other side, the bedrock will fall down. Gohma’s armor will begin to crack and she will lift the bedrock back up. This causes rocks to be thrown away in every direction and might hit you unless you avoid them. Repeating the bedrock to fall down 3 times will break the armor and Gohma will be possible to hurt for real. Make sure to stand behind Gohma the third time, so that you land in front of Gohma, which will allow you to damage her quicker during the next phase.
The second phase is where the HP starts to decrase. There is a total of 10 HP before Gohma is defeated and the only place where she can be harmed is her eyeball. In a normal speedrun the grappling hook and your sword represents the damage given.
Target her eye and throw the grabbling hook at it. The throw will take 1 HP and drag her down to you. Use your sword to take away more of the HP before she get’s back up by performing spin attacks or slash her normally. Your goal is to take away 4 more HP before she pulls herself away from you. The easiest way to succeed with this is by doing spin attacks, because sometimes she pulls herself back before you are “done”. Repeat this twice to beat her.
If you have been using the Bombs Early route you can kill Gohma slightly faster with the use of your bombs. Drop a bomb and drag her to you. This prevents her from pulling herself back early and the bombs takes away 4 HP right away. It is even possible to defeat Gohma in a single cycle with the use of bombs, but it is pretty difficult.
This trick is generally slower due to the grapple animation being slow, and gohma's death coming later compared to just killing it with your sword.