Behind the Waterfall

This mission is unique to the Nintendo DS, but was based off a mission in the N64.
We enter Hazy Maze Cave and go to the underground lake. We get a 1-up on the way. We climb onto Dorrie's back and steer toward the double doors that we can't reach. We get the yellow cap off of Dorrie's head and go through the double doors. We go into the inky pool and see some Snifits. The Hazy Maze Cave music still plays. Around the corner to the left is a Power Flower. We get it and transform into Metal Wario! We get a message: "The Power Flower turned Wario into a metal machine! When he's metal, he can walk underwater! Try it!"
While powered up, we get the four Red Coins that are underwater near the island near the waterfall. In the alcove near the second bridge, we find two more Red Coins and a Bob-omb Buddy who'll tell use where to find the rest. We have difficulty jumping to the island with the last two Red Coins, so we get the Power Flower so we won't be swept away by the current. Just before we can get the Power Flower, we lose the yellow cap from a Snifit and get the Power Flower as Mario. This works, as there is another Star here that only Mario can get. We make it to the island and get the last two Red Coins. The Star appears underwater.
Star Get #49, 35 Coins, 5 Lives
Getting the Red Coin Star takes us out of Hazy Maze Cave, so we go back in. We jump to avoid a spider and fall into the abyss.
Take 2- We take a hit from a bat and a rock and get a 1-up. We need to be Mario to get this Star, but there are caps in the area. We steer Dorrie back to the double doors. We take a hit from a Snifit and the current takes us away and dumps us outside the castle near the waterfall.
Take 3- We take a hit from a spider and get a 1-up. We jump off the elevator and take damage. We go back into the inky pool and take three hits from Snifits, losing the green cap we accidently picked up. We reach the island near the waterfall and get the Power Flower. As we float straight up, we see coins in an arrow formation pointing up. Above it is a Star.
Star Get #50, 22 Coins, 6 Lives
We get a message: "You've recovered 50 Power Stars! That's enough to open the Star Door on the third floor. Bowser's closer... Eek! But before you move on, make sure you found the ? Switch and hit the ? Blocks. Hurry along, now. The third floor is just ahead."
Wow, I actually did one of the things the message told me to do before it mentioned that I should have. I've already taken care of the ? Switch. I would have to open up much more of the castle to get 50 Power Stars without it. It already assumes I've beaten Bowser a second time. We're not quite there yet, but we'll keep going.
The next Star is Elevate for 8 Red Coin.