The Ugly Mermaid

The Ugly Mermaid is the eighteenth episode of The Adventures of Super Mario Bros. 3; it aired alongside another episode of The Adventures of Super Mario Bros. 3 entitled "Mush-Rumors".

Plot Synopsis
The episode begins in Water Land as Bowser's Doomsub swiftly makes its way through the ocean, planning to conquer the underwater world of Mertropolis, which he plans to turn into Kooptropolis. Already aware of his plans, Mario, Luigi, Princess Toadstool, and Toad pursue the sub, aided by Frog Suits.

Hip and Hop Koopa notice them and inform Bowser, who orders his Rocky Wrenches to attack. The Mario Bros. manage to catch some of the wrenches that are thrown at them, and throw them back, damaging the Doomsub's propellers. The submarine spins out of control, firing strange beams in all directions. One of them hits Mario, encasing most of his body in a block of cement, which causes him to begin sinking.

When all seems lost, a mermaid named Holly Mackerel comes out of a Warp Pipe and swims over to save Mario. She introduces herself as the mermaid princess of Mertropolis and brings Mario to the submerged city, which is covered by a dome. Luigi and the others follow, and try their best to revive the now-unconscious Mario. When he regains consciousness, Holly tells him that her fortune teller claimed a frog prince would "come hoping into my life". Believing Mario to be that prince, she falls in love with him and tries to get him to marry her. After some brief dodging and running away, Mario directly confronts her and tells her that they just aren't compatible. Leaving her in tears, he and the rest of the team head back to the pipe leading to the ocean. However, before entering the pipe, Mario can't bring himself to go back. His near-death experience has made him dreadfully afraid of the water, and he refuses to leave. The others try to convince him to go, but he makes it clear that he won't go into the water ever again. Suddenly, the Doomsub appears over the city, and Bowser shouts his demands through a loudspeaker, declaring that if the city isn't surrendered in twenty minutes, he'll destroy it. King Mackerel shows up, and worries about Mertropolis being destroyed.

Luigi, Princess Toadstool, and Toad jump into the exit pipe, but Mario's still too afraid. Peach tries to convince him that everything will be okay, but it doesn't do any good. Suddenly, two Boomerang Bros. enter through the pipe and start attacking the city. Mario defeats them, but just as soon as they're gone, more arrive. After Mario's group battles the small troop of Boomerang Bros., Bowser announces that he has more to come. As before, Mario's too scared to leave the city. Princess Toadstool tells him to stay behind, while she, Luigi, and Toad stop the Doomsub. Holly sees that Mario's still there, and misinterprets his staying as a sign of love for her. King Mackerel still sees Mario hanging around, and warns Mario's about Bowser's threat. Holly introduces Mario to her father, and plans to prepare a wedding ceremony, much to Mario's dismay.

Onboard the Doomsub, Hip and Hop spot Luigi, Princess Toadstool and Toad returning, and Bowser responds by firing Nasty Nets at his three foes, capturing all of them. Back in Mertropolis, Holly tells Mario about how she's inviting all of the citizens to their wedding. However, Holly's plans are cut short when Bowser announces that he's going to throw them a wedding shower. Bowser then drops a Bob-omb onto the city's protective dome, blasting a hole in it, which causes water to pour in and start flooding the city. Mario regains his courage, realizing he's the only one who can rescue his friends and the city- That, and he wants to get away from Holly. He swims up the advancing flood of water, and fixes the hole in the ceiling on his way out with a manhole cover.

The Doomsub fires a Chain Chomp at Mario, but Mario grabs ahold of the chain and uses the Chomp to cut open the Nasty Nets that are holding his friends. Mario and Luigi then take one of the nets to capture a school of Jelectros, and hurl the net at the Doomsub. The Jelectros electrocute the Doomsub, forcing the Koopas to retreat.

Later on, back in Mertropolis, King Mackerel presents Mario with a medal for his heroic deeds. Holly, still infatuated with Mario, arrives and puts a wedding-day helmet on him. The helmet, however, distorts his facial appearance, and she shrieks in shock, saying that she can't marry him because he's "the ugliest frog she's ever seen." With that resolved, the heroes cheerfully head home to the Mushroom Kingdom before Holly has a chance to get over her fear.

Trivia

 * The opening music is different from normal, it has more of a sea-like theme instead of the standard theme.
 * The citizens of Mertropolis are unable to breathe the air, yet no explanation is given as to why they live in air-filled city (or why they panic when Bowser floods the place).
 * This is the only episode where Mario and the others are in the same powered up form during the entire episode.
 * The merpeople in this episode are inverse of the typical version. Usually, they are depicted with a human upper torso and a fish-like lower torso (fins instead of legs).  In this episode, the upper body is fish-like and the lower body is human-like (legs instead of fins).