To reach the area with the next dungeon, warp to the House of Gales and go one screen right, one screen up. In the last screen, head for the top-right corner, where Racing Bro stands; to his left will be a doorway to Lorule–merge into the nearby wall and go through the doorway.
In Lorule; bomb the cracked wall to the left to reveal a hidden cave with fairies inside. Next, go right from the doorway and climb up the stairs to get up the hill. Merge into the wall above and walk all the way left to find a small ledge with a single skull–break the skull to reveal Maimai #72 .
When you’re done, drop down from the ledge and head for the exit in the bottom-right corner. In the next screen, make your way down and at the end you’ll find Maimai #73 on the wall–emerge behind it to prise it off. Then turn left for the exit. Now you will be in the main area. Dive into the water above and swim for the turtle to the left; Mama Turtle will ask you to look for her missing children. From Mama Turtle, swim all the way up, past the fiery island. Eventually you’ll come across Maimai #74 submerged in the middle of a small rock formation.
From the Maimai, continue swimming up and exit to the next screen; at the end is a doorway to Hyrule, for reference. For now, return to the previous screen and swim all the way left. At the end you’ll find stairs leading back to land. From here, swim down to find a turtle being harassed by Kus; kill all four Kus and the turtle will leave for safety. Next, go back up and ascend the stairs. Turn right and merge onto the nearby wall, then walk right. After a while you’ll see a turtle stuck on the wall; emerge while behind it to get it off.
Return left and up the stairs again. This time, head up for the next screen; here, slay the Taros and open the chest containing a nice 100 rupees , then go back. Make your way down, while keeping to the left, and you’ll find the Item Seller; continue all the way down to find Maimai #75 glued to the wall.
Merge onto the wall below and walk left; at the end is a doorway to Hyrule on higher ground and a beached turtle below. Drop down and lift the big rock further down to uncover Maimai #76 . Then walk toward the panicked turtle and press A to shove it off-shore.
Mama Turtle will have reunited will all three of her children and, to reward Link, will offer him a ride on her now-taller shell. Swim right and locate Mama Turtle–she will be slowly swimming around in a big circle. When she comes, walk up her shell from her back, then wait until she reaches the top-most part of her journey. At this point, walk up to reach the platform on the fiery island. To progress, you will need the Ice Rod. Wait for a blast of lava ahead, then cast the Ice Rod at it; merge into the solid pillar to cross the gap and enter the dungeon.