After Nav-Com helps you track down Dr. J's signal, you enter the underground ruins near Howduyadu-cola.

Explore the Cave

Go north from the entrance.

There are four Loopers here, but you can ignore them and go north to the next room.

Go to the left and take the Anklet. You will change color. Now you can jump over gaps that are two squares wide (you can still jump over gaps that are one square wide as well). So jump north onto the tile, then jump onto the switch, and do the same with the other tile. Then get the two double hearts that appeared. Then go north to the next room.

NOTE: you can't jump over two-square gaps anymore! The effect wore off when you left the room where you got the Anklet. From the entrance, go left until you can jump over the water to avoid getting trapped by Muumus at the entrance of the room. Kill all the Muumu mummies and go west through the passageway that opened.

Go south, then jump west across the tiles. Pick up the Anklet that appeared on the last tile, then jump east and go to the eastern wall. Then go north, and at the north end of the platform, jump west onto the tile that you can now reach with the Anklet. From the first tile, jump north, then from the second tile, jump west. Kill the Octot, then go back east to the solid platform. Go south, then west, and jump onto the tile that has a footprint on it. Jump north from there and kill the Octot, then jump west onto the tile that the Octot was on. From there, jump north, then west, and kill the Octot if you have the Shooting Star available. Then jump south and kill the Octot there, then jump west, then north, then west twice, then kill the Octot to the south to open the door. (If it doesn't open, go back east and look for any Octots you missed.) Then go west through the door.

Carefully jump west onto the square-shaped platform, and jump up and down on the leftmost disappearing tile to wait for a gap between the Muumu mummies. Jump onto the square platform when there is a gap, then keep going around the platform while you hit the Muumus, then jump on the switch to open the treasure chest in the middle, revealing a double heart. You can stand there to hit the Muumus as they go around. When they're all gone, the north door will open, but before you go through, jump onto the tile in front of the door, then jump east to find an invisible tile. Jump east again to find another, then jump east one more time to reveal a Magic Potion. Get it, then go north through the door.

Kill the Nautilus to make the north door open. Go through and you will battle Giant Turboss.