Mario and Yoshi came back to Peach's Castle from Sunset Islet. The sun was just setting under the hill and the sky was now red. The two crawled into an underwater tunnel, believing that's where they should go next.

Crystal Caves

The Crystal Caves were underwater caverns filled to the brim with white shiny crystals (hence its name), spiders, falling rocks, water, a submerged castle, and mermaids. Mario and Yoshi have explored caves many times before, but this cave had branched pathways and lots of dangerous traps that could get in the duo's way.

Star #1: The Cracking Cave

Mario and Yoshi trekked down slowly into the deepest parts of the cave where water resided. It was dangerous though because they had to watch for falling rocks! Mario even pulled Yoshi out of the way to dodge one.

Yoshi: Yipes! That was close! Thanks Mario.

Mario: I've got your back, buddy.

As they walked up to where the star was, Mario felt déjà vu from this place.

Mario: You know, this kinda reminds me of Hazy Maze Cave, don't you think?

Yoshi: Yeah… I can kind of see it.

Mario and Yoshi got the star and teleported back to the start.

Star #2: Underwater Race

Mario and Yoshi went into a cave where a new green cap resided. The shape resembled a frog.

Mario: (Oh no… Don't tell me we have to use THIS.)

Yoshi: What's this?

They put on their caps and became Frog Mario and Frog Yoshi. They both wore green suits resembling frogs. Yoshi especially looked ridiculous in it since he was already green.

Yoshi: What the-!?

Mario: *sigh* The Frog Suit. I had to wear this stupid thing at a play I performed in a couple years ago. Not only did I look ridiculous, but I had to hop around like an actual frog. Who the heck does that!?

Yoshi: Well, this isn't a play, so I'm sure we can still walk.

Mario: Alright, but still. I hope nobody has to see us like this.

Yoshi: Yeah, same with me. I don't like this.

They walked into a blue cave where mermaids resided. They looked puzzled seeing a human and dinosaur in frog costumes in their cave.

Yoshi: (Well, this is awkward.)

Mario: (And… they're staring.)

The mermaids were beautiful looking, but they didn't seem too friendly.

Mermaid: Do you have any business around here? We mermaids do not like being talked to by random strangers…

Mario: Um… sorry ladies. We were just looking for stars around here. Have you seen any around here?

Mermaid: Hmm… go talk to that mermaid sitting on the shore. She might know something.

Mario and Yoshi went over to the lonely looking mermaid sitting at the shore. She looked at them with a smug impression on her face.

Mermaid: Hey, losers! Do you think mere landwalkers like you would stand a chance in a race against us mermaids? If so, prove it!

Mario: A race, huh? Alright, miss. We accept! You know Yoshi, if there's one upside these suits have, it's that they make water levels a whole lot easier. You'll see what I mean.

Yoshi: If you say so.

The mermaids giggles and then the three start swimming through the caves. The mermaid was winning at first, but Mario and Yoshi went through rings to gain speed boosts and ultimately win the race. The mermaid admitted defeat and rewarded a power star.

Star #3: The Water Temple

After finishing the race, Mario and Yoshi reverted back to their normal forms and swam over to a water temple they swam by.

The inside was made up of gray tiles and despite being called a 'water' temple, there was actually no water in it at all. It had three rooms and several Warp Pipes, which lead to an alternate version of the temple with some minor changes.

The room on the right had a closed gate; it required a key to open it. The room on the left had nothing at first, just a lone tall platform. The room in the center had a bridge platform held by a pushable block. The two heroes had to push the block until the platform reached the other tall platform leading to a pipe. Then, when they reached the other side and went through the pipe, they ended up in the alternate version of the temple; the tiles were bright blue and the bridge platform was absent. Luckily, the platform had a key, so Mario grabbed it and went back to the main room to enter the main pipe.

Back at the real water temple, Mario and Yoshi head to the closed gate and open it with the key. On the other side was an orange button. When it was pressed, it made a green path of blocks appear leading to another pipe on the right side of the room. On the alternate water temple, there was a blue switch after Mario and Yoshi emerged from the pipe they just entered. They pressed the switch, which caused another green path to appear, but not in this version.

They appeared in the real version in the room on the left. The green path lead to another pipe, and once the duo emerged from it, they finally saw the Star.

Mario: Thank god that's over.

Yoshi: Yeah, that was tough. But at least we made it.

Star #4: Save the Mermaids

A giant pink fish with blue fins had escaped from its cage and began to terrorize the mermaids.

Mario: Oh no!

Yoshi: That fish doesn't look friendly.

The same mermaid who the two raced with earlier approached the heroes in panic.

Mermaid: Mario, Yoshi, we really need your help! The sea monster we had caged in here somehow escaped! Can you try and lure him back to the cage? You beat me in a race, if not you, no one can help us mermaids out of this misery!

Mario: We're on it!

Yoshi: Question is, how are we gonna do that?

Mario: You got any food to use for bait? Cause I am not risking getting eaten myself, and I don't want you to do that either.

Yoshi takes out a tomato.

Yoshi: Well, I was gonna save this for tomorrow, but if you need it…

Mario snatched it and caught the fish's attention.

Mario: Here, fishy fishy!

Mario threw the tomato into the cage and the fish started eating it.

Mario: Now, Yoshi!

Yoshi used his tongue to trap the fish in and the mermaids cheered.

Mermaid: Thanks for helping me! I don't know how I could thank you… Weren't you searching for Power Stars? It's not much compared to what you did to us…but maybe it helps repaying just a bit of our moral debt to you!

The Mermaid reward the heroes with a star.

Mario: Thanks! And this is plenty!

Mario and Yoshi: Yahoo!