After you reach Dragon Roost Island, you follow Medli into Dragon Roost Cavern.
Enter the Main Dungeon
Pull the left block out from the wall, then pull the middle block to the side to open the way. Go through. Kill the two bokoblins. Pick up one of the burning sticks that the bokoblins were carrying. If the flame goes out, just walk up to a burning torch to light it again. Light the two unlit torches. Open the chest to get a key, and go to the next room.
Use your sword to break through the wooden planks ahead. Go through and pass the locked door, then continue on the ledges. At the second ledge, drop down and pull the block out of the wall. Climb onto it and jump to the next ledge from there. When you're on the rock, wait for the geyser to stop shooting fire, and jump across. If you fight the keese, be careful not to cut the ropes of the bridge. Bomb the rock in front of you, and go through.
Get the Map
The pots around you have water in them, as indicated by the water droplet symbol. If you toss one into the lava, a piece of lava will harden for a while, then eventually it will turn back into regular lava. Throw some water onto the lava near the chest, and jump over to get the map. You might have time to use the same lava platform to get to the other side of the room, but if not, just throw another water pot. Start climbing up the ladder, but if you hear the "monster approaching" music and a squishy sound, get off of the ladder and walk back a few steps. The chuchu will fall to your level. Kill it and gather any chu jelly it might leave behind. You can use it at the Windfall potion shop to create potion. Go to the next room.
Get the Compass
Walk up to the wooden planks in front of you and a bokoblin will attack. Kill it and take its sword. Use its sword to break the planks to your right. You'll see more planks ahead of you. First kill the chuchus, then break through the planks with the bokoblin sword, and open the chest to get a key. Turn around and head left, kill the chuchus by the door, and go through.
To your left, throw something at the bomb flowers to set them off and break the rock. Go across and through the locked door.
Go straight, fight some chuchus, and break the planks to your left. Kill the bokoblin and take its stick. Light it with the torch, burn the planks, step on the switch, then stand near the door where you entered the room and turn left. Stand on the edge, and throw the burning stick with A to light the planks over there. Now go through the door you opened when you stepped on the switch.
Over on the rope bridge, run to the end right where the bokoblin is standing so your sword won't cut the ropes when you swing it, and kill the bokoblin. Go up the ladder and stop before you reach the part that's darker gray. Let the flames shoot out, then go on up. Kill the kargaroc up here (they leave behind golden feathers), then sidle across the ledge until you're just next to the hole in the wall. Wait for the flames to shoot out and stop, then sidle past. Go around the rock, then hang from the ledge on your hands, and hit left on the D-stick to make your way across. Climb up when the wood widens out. Jump up on the small ledge, then turn around and jump onto those planks. Pick up the bomb flower to your left, and turn around and throw it where the big rock is. Go in the door you just opened.
Pull out the middle block, then pull out the block on the right. Climb up the blocks to get to the passage at the top middle. Avoid or kill the rats, and pull out the block. Climb on it, and open the chest to get the compass. Now break the jar and light a stick, then throw it at the planks across the way. Open the chest there to get a key. Go through the door.
Open the Warp Jar
Go up into the nest and hit the kargaroc. This will move it out of the way so you can get the key that it was sitting on. You don't necessarily have to kill the bird. With key in hand, go through the door.
Break the jar ahead to get some sticks. Light one and take it with you. You can use it to kill the keese, or drop it and use your sword on them. Light the torch here and open the chest. Get your stick again, and if it has gone out, light it at the torch. Burn through the planks, light the torches here, then go through the door.
To your left is a warp jar covered by a rock, and to your right is a bomb flower. Use the bomb flower to open up the warp jar. Then go across the bridge and through the door.
Kill whatever monsters are around, then break as many jars in the room as you can reach (including one on a ledge) to find and kill the remaining bokoblins, which will open the doors. Before you leave, light the torch to reveal a chest containing treasure chart #39 Now climb up and go through the door.
To kill the magtail in the middle, you can use a parry attack, but be careful because you might end up falling off into the lava after parrying and will have to start this room over. Try not to get too close to the edge before parrying. You can also throw a water jug onto the magtail to try to get it out of the way, but it doesn't stay down long. When you can, carry a water jug to where the magtail was and throw it where the flames have been shooting up. Jump on the platform and wait for the flames to take you up. Jump onto the ledge and go through the door.
Use a bomb flower on both rocks to reveal a warp jar and a door. Go through the door.
Rescue Medli and Get the Grappling Hook
Without stopping, run up the stairs, and go into the area where Medli has been locked up. Kill the bokoblins and the moblin. Moblins leave behind skull necklaces.
Talk to Medli. You'll receive the grappling hook. Go up the stairs to the left of Medli's cell, then grapple onto the pole the way that Medli told you. Swing over and keep going until you get to some planks. Cut them, drop down, and go into the door behind you. Just ignore those other grappling poles for now.
Get Some Treasure
Use the warp jar in this room to return to the first room of the dungeon with the bokoblins in it. Kill them, then go through the door behind them. Go through the first door on the left. To your right will be a grappling pole. Swing across to reach a chest containing treasure chart #11, then swing back.
Go back to the warp jar in the first room. Use it twice to get to the dark green room, then go through the door on the right. It's the same door that led to Medli. Turn left and swing on those grapple poles that you ignored earlier. If you need to change the direction you're swinging, just hold R to stop, then press left or right on the D-stick, then let go of R. After grappling your way across, go through the door.
Cross the rope bridge, killing the bokoblins you encounter, then cut down the ropes of the bridge and walk on it until it falls. Open the chest that just appeared to receive a Joy Pendant, and go through the door here.
You'll see a cage to your left. Jump inside. Your goal is to cut the three ropes at the same time using a spin attack, to make the platform drop down. If you wait until the flame is shooting underneath the platform, it might be possible to cut each rope one by one without falling to your doom. Otherwise, when the flame isn't hitting the bottom of the platform, face away from all the ropes, swing your sword and hold B to get ready to do a spin attack. Then go directly to the middle of those three ropes by centering yourself on the swirl symbol, and do your spin attack. If you do it incorrectly and only cut two ropes, you fall, get burned, and have to try again. When you do it correctly and your platform is down below, go through the arch and jump along those platforms to continue, and go up the ladder. Up here, turn to the left and use your grappling hook to look above you. Grapple from that bar in the ceiling to open the door. Go through.
Tingle Tuner Note: If you have the Tingle Tuner, use it in this room and use a Tingle bomb on the question mark across from you. This reveals a chest that contains the first Tingle Statue. You can only reveal these chests with Tingle bombs, not regular bombs. Grapple straight across to reach the chest.
Get the Big Key
Next, grapple, then hold R to stop, and press the D-stick so you're facing the other passage. Swing over, then jump across all of the platforms, and swing over to the door and go through.
In here, hit the magtail twice with a regular attack to make it roll into a ball. Then pick it up and put it on the switch. Open the chest to get the Big Key, then leave the room.
Go to the Boss Room
Kill the keese that are now in this room, and grapple back until you reach the first grapple pole. For the last jump, hold R to climb up the rope a little bit, or you won't make it. Now make your way back to that platform that was in the cage, and go up. Go through the door here.
Pick up a water jug and throw it onto the shooting flame. Go to the top and go through the door to your right.
Outside, turn right and grapple your way up. Eventually you get back to that dark green room.
Above the lava there is a grapple pole, so use it to get across. You can kill or ignore the magtails. Open the chests to get 10 rupees and a knight's crest. Then break a jar near the door to reveal a fairy. Catch it in your bottle. There is another fairy in the other jar by the door. Now use your Big Key on the big locked door.
Figurine Gallery Note: You can't take the gallery picture for Gohma now because you do not have the color picto box, but you will have another chance before the end of the game.
To defeat Gohma, grapple onto Valoo's tail, which is hanging from the ceiling, then swing and jump off on the other side. This will cause a piece of ceiling to crash down on Gohma, cracking its carapace. Do this three times to make the carapace come completely off. Then lock on to Gohma and grapple its eye to bring it near, then slash away with your sword. Repeat this strategy until Gohma is defeated
Now you have Din's Pearl.
If you haven't purchased bait yet, go to Beedle's shop going around the island, and buy the bait bag, three hyoi pears, and fill the rest of your bag with all-purpose bait.
Check the postbox here to see if you have any mail.
Now go talk to your boat. He tells you that the wind needs to be blowing south. Use the Wind's Requiem that you learned earlier. The compass arrow will point in the direction that you press the D-stick. Press the D-stick down to make the wind go south.
Then get into your boat, turn to face southward, and use the sail.
Soon, a fish guy will talk to you. He will fill in this square on your Sea Chart, and will tell his fish friends to do the same for you. Whenever you see a fish jumping out of the water near an island, go up to the fish until the yellow arrow appears above his head, stop the boat, and throw out some all-purpose bait. He'll fill in that square of your Sea Chart.
You can look at any treasure charts that you have by pressing up on the D-pad (not D-stick) and press Y while viewing your sea chart. If you have a treasure chart for Dragon Roost, don't use it yet. It is a chest containing 200 rupees, which is all you can carry right now, so if you get it now (unless you have absolutely no money) it will be a waste.
Now go south. You can fill in the squares of your sea chart as you go, but you don't have to. If you see seagulls flocking, or if you see a giant cyclone, stay away. Directly to the south is Fire Mountain.
If you see glowing circles on the water, they are usually chests containing either 20 or 50 rupees. To get these, just cruise up to one side of it and it will disappear, but the humming sound will get louder. Then use your grappling hook on the side of the boat that the circle was on to raise the treasure.
Get an Empty Bottle
To get to your destination, continue south from Fire Mountain to reach Eastern Triangle Island. There might be a boat of divers at Eastern Triangle Island. Talk to them if you see them. From there, go south to Bomb Island. Slightly to the southwest of the island is a submarine. Go to it and walk in. Kill all the bokoblins, watching out for the rats, and a chest will appear that contains an empty bottle.
Get 20 Joy Pendants
Now leave the submarine. There is something that you can do now to save time later, but it's kind of tedious. To beat the game, you will eventually need to collect 20 joy pendants. You'll find them scattered around the world and in every dungeon, but you can get 20 right now if you wish.
There is a bokoblin on a raft near the submarine. If you use your grappling hook on the bokoblin, you steal a joy pendant from it. Then you can go back into the submarine and back out to reset the bokoblin, allowing you to get infinite Joy Pendants. Do this until you have 20 Joy Pendants. You might want to get 50 because you'll have a need for them later, but it's not necessary yet. You can always come back and do it later when you have collected more joy pendants and don't need to collect so many from this bokoblin.
Go to the Forest Haven
South of Bomb Island is the Forest Haven, which is your destination.