After you defeat Giant Turboss in the first cave of chapter 6, you reach the second part of the cave.
Continue Through the Cave
After you go west from Giant Turboss's room, jump onto the tile to the north, then jump on the switch, then go north through the door.
Kill the three Nautilus, then go north through the door.
There is a shadow on the wall, but it doesn't lead to the correct place. Go to the southwest corner of the room and go west from there to go through a hidden tunnel. Jump on the tile, then jump on the switch. That will open the north passage. Go back east through the wall, then go to the northwest corner of the room and go west through the wall. Go west, take the Anklet, go west until you can't go any farther, jump west to step on a switch, then go close to the east wall without going through, and jump south. Go west until you can't go farther west, then jump west to activate a tile that lights up the room. If there isn't a switch to the west, jump north and jump on the tile, then go east until you can jump south, then jump west from the tile onto the switch, and take the double heart. Jump back onto the switch that you stepped on a moment ago, and jump south, then jump west to step on the switch there. Go north to get Baseballs. Then jump east until you can go north to the next room.
Go west to get some Baseball Cleats. Press SELECT to switch to the Baseball Cleats, then use one to kill all of the squid in this room. Then go west through the passage that appeared.
Go south and kill the Nautilus there, then go west and jump on the tile to reveal a double heart. Before you try to get the double heart, go east to the east wall, then go north to the north wall, then go west and kill the Nautilus there. Go west and jump on the tile there. Go south to get the Anklet that appeared. Then jump west off of the tile, then jump north onto the tile in the water. Jump west from there to get the double heart. Keep jumping west to get another double heart. From that double heart, jump south. If you need another double heart, kill the Nautilus to the east, and go east and jump on the tile to reveal another double heart. Jump north to get the heart, then jump south. Go to the north part of the platform and kill the Nautilus there to open the door. Go through.
If you have Cleats, use them to damage all the Muumus at once. You can use three Cleats to kill all the Muumus. When all the Muumus are gone, go north through the door.
Kill the two Loopers and go north through the door. Now you must battle Broken Joe.