First, go to the right and run your way up the hallway of rolling boulders, but don't stop in the small area to the left, because it's a trap. Instead, just weave around the boulders and go up the hallway, then walk to the left and go up to the blue tiles. You will notice an eye switch. Hit it with an arrow to open the door to the left.
Open the chest to get one rupee. Then three stalfos will attack. You have to kill them quickly, because otherwise they will keep regenerating. When you defeat them, you get a small key.
Go down the hall of boulders, then go up the stairs to the north and unlock the door and go up the stairs.
Go across the spiky bridge to the north. Then jump down on the right side of the spiky bridge. Avoid the sand monsters since none of your weapons can harm them, then go east. Go north past the rolling spiky things and up the stairs.
Down below, kill the three stalfos, then go around and get the Sand Wand. Just tap the sand to make it rise up. You can tap the sand that you are standing on. The wand can be used to raise you up or to create walls around you. It can also kill the sand monsters that you passed earlier.
Go back the way that you came and use the Sand Wand to raise yourself up to the ledge to the left of the door. Then go downstairs.
Floor 2, part 2
Use the Sand Wand to block one or two of the rolling spike things. Get yourself up onto the left ledge to receive 20 rupees. Use the sand to block the rightmost rolling spike thing so that it stops and acts as a bridge to give you access to the treasure chest on the right.
Go to to the lower left corner of the room and use the wand on the sand monsters until they become solid. Hit them with your sword or pick them up and throw them until they crumble.
Go up and use the sand to go to the upper ledge, then use the sand to block the rolling thing and use it as a bridge to go back down the stairs.
Floor 1, part 2
Use the sand to reach the treasure in the middle of the room to the left of the stairway blocked by the stone slab.
Go to the top of the room where you shot the arrow through the boulders before. Use the sand to move the boulders out of the way of the eye switch, hit it, and use the sand to raise the monsters out of the sand. Kill them while they are stunned. Then open the chest that was revealed to the left. Then go down and hop down the ledge by raising yourself up with sand.
Go to the lower left area and look at the ledge above you. There is a rolling thing. Push it off of the ledge to the left. Then go to the left and push this rolling thing off the ledge to the left. Use the whip to go to the right, then go up.
On the left, there is a lower eye switch and two upper ones. Hit the lower one, then raise yourself up and hit the upper two. Then go through the door that you just opened.
Stand in the gap to the right while pushing the rolling thing downward with sand. Walk up above and get yourself onto the left ledge with the sand. Use the sand to bring the rolling thing back up so that it is between the two sets of stairs. Cross the rolling thing to get to the other side. Then use the sand to bring the rolling thing down to the lower set of stairs. Go across it.
Kill the sand monsters, then go back and get the 20 rupees from the treasure chest that was revealed. Go back to where you fought the sand monsters. Use the sand to raise yourself over the short wall so that you can read the sign on the wall. It says "between one and three is where the key hides." Where have you seen three eyes? Go to the midpoint between the line that you can draw between the three eyes and the single eye. That point is slightly above the middle of vertical sand hallway in the upper middle part of this floor.
To reach it, go to the right and go across where the boulders are rolling. Use the sand to get up onto the ledge, then run to the top and hop down as soon as the boulders pass. Then quickly run up to the left area. Use the sand to get onto the ledge, then use the wand in the vertical sand hallway as described above to reveal the key.
Now hop down to the middle of the room. Move the large boulder onto the wooden platform with the hammer below it. Hit the crystal switch to hit the boulder and knock it into the cracked wall. Go down the stairs.
Use the wand to go across the quicksand. Unlock the door with the key that you found as described above.
Freeze the two sand monsters and put them onto the two switches to go through the door to the right.
Use the wand to go across the quicksand to the left and deflect the arrows with your shield to reach the stamp station.
Use the wand to go back around. Run past the arrow shooters and get to the ledge at the upper right of the room.
You need to roll the block so that the blue crystal goes into the blue hole in the floor. Roll the block to the right, down, right, up, left, and down. Go through the door.
Use the sand to stop a boulder and roll it onto the wooden hammer platform. Stand on the switch to create a bridge, then use an arrow to shoot the crystal switch, cracking the stone slab with the boulder. Then stop another boulder with the sand and roll it onto the switch to make the bridge reappear. Go down.
In this area, you can go north and create a bridge over the quicksand to reach a treasure chest that contains 20 rupees. Go left and press the switch for a shortcut back to floor 1.
To open the blue door, you need to put the two blue crystal switches into the two slots. Roll the rightmost block down, then left, then down. Roll the leftmost block right four times, down, left, up, left, and down.
Go to the bottom left through the door that opened. Hide in the gap to go past the rolling spiky thing. Kill the stalfos in the next room to reveal a treasure chest, then use the sand to stop the lower rolling thing and raise yourself up to it, then go down and step on the switch. Jump down and stop the upper bridge and raise yourself up to it, then go through the door that you opened.
You'll be attacked by some monsters in the sand. As before, use the wand to raise them up onto the sand, then hit them while they are stunned.
Go up through the door. Use the wand to raise up all of the sand. There are rupees hidden here, and the Big Key is hidden in the upper right area. Take the key back to the central area and put it down so you can move the blocks to put both red crystals into their slots.
Push the rightmost block down, left, up twice, then right. Push the leftmost block left, up, right, down, right, down, and left. Create a bridge across the sand with the wand, then carry the big key over and put it into the big lock. Go up the stairs.
Up ahead, you will fight Skeldritch.