(At the beach, Candace is beginning to relax)
Candace: Ahh, a nice relaxing day at the beach. Nothing but the waves, the sun and peace and quiet...
Baljeet: Buford drank all the sunscreen!
Buford: Coconut is my favorite flavor!
Isabella: Who wants to play volleyball?
Candace: I spoke too soon.
Linda: Oh, Candace, look, there is a sandcastle building contest over there. You used to love those. You should sign up!
Candace: Yeah! Wait... (mutter) Why brother? With these two here, there will be no competition. They'll build a real skyscraper out of sand, with a working elevator, and window-washers, and a parking garage with flying cars! They'll totally steal my thunder!
Phineas: Actually, there are something else we may be doing today. With a minimal amount of research, Ferb found out that the lost city of Atlantis is probably located right off the coast of Danville!
Isabella: Ooh! I hope I will see a real life seahorse! And get my Underwater Equestrian Patch!
Buford: I'd like to see a shark! I heard that those are the toughest fish in the ocean.
Irving: I got in the car when your mom stopped for gas. I'm just happy to be here.
Buford: Wow...
Irving: Ooh, and I bought my camera, to take pictures of all the action!
Phineas: Guess we know what we're doing today. Hey, where's Perry?

Male singer: Doo wa doo be doo wa doo be doo be doo wa. Thank you, thank you very much.
(Perry jumps into the man's guitar case)
Agent P !
Carl: (Imitating Major Monogram) Ahh, Agent P! Dr. Doofenshmirtz has been to every plant-nursery in town, buying up little seedlings and now he's out with he's blimp. Find out what he's up to!
Major Monogram: Carl?
Carl: Ohh... eheheh... sir?
Major Monogram: Are those my old mustache clippings?
Carl: Some of them?
Major Monogram: Sorry you had to see that, Agent P. Please find out what Doofenshmirtz is up to!

Phineas: Hey, Mom! We're gonna go find the lost city of Atlantis! Be back later!
Linda: What some imaginations...
Candace: Mom! Oooh! They're leaving! Mom, get out the turret molds. We've got a sandcastle to build!
Phineas: Okay everybody, follow me! And remember, if you get lost, the surface is up!
(They all walk down to the sea floor)
Irving: Wow! Is that the Titanic over there?
Isabella: Look! It's Amelia Earhart!
Baljeet: Ah, the tomb of Poseidon.
Phineas: Focus, guys. We're looking for Atlantis, remember? (to Ferb) Which way, Ferb?
GPS: Take phytoplankton road north.
Irving: Hold it! (He takes a picture) That one's for my wallet!
Baljeet: Why is water always so warm next to you?
(Up at the sandcastle building competition)
Linda: I'm so glad that you wanted to join the contest. This'll be fun!
Candace: If we're going to do this, we gonna do it right! Here, fill these buckets with water, I'm going to go find some sand.

(DEInc. instrumental)

Doofenshmirtz: (Spraying the plants in his blimp) Lunchtime, my little plant friends! Yes, you like your water, don't you! Everyone gets H2O, even you little... Oh, Perry the Platypus! You landed into my fertilizer trap! Look at you. You've potting soiled yourself! (He laughs) So, I got to thinking, why use animals or insects to aid in my evil scheme, when there are these shiftless do-nothing-plants just laying around? So, I've created a super evil growth formula, that when sprayed on my plants, that will turn them into thorny, prickly minions! With them under my control, I will rule the Tri-State Area with an iron fist, and a green thumb! Hahahaha... (He sniffs) And, if you don't mind, I'm going upwind of you.

Phineas: We're almost there, guys!
GPS: Turn right at kelp.
Irving: These sculls are pretty cool! (An eel takes Irving's camera) Hey!
Phineas: It's okay, Irving, you still have the greatest camera ever made.
Irving: Where?
Phineas: Right here, the human mind. You can take pictures with your mind and store them in your memory. Try it!
Irving: Okay... Click! Well, I guess that worked...
Isabella: Seahorses!
Baljeet: You can get your Underwater Equestrian Patch now!
Isabella: Umm... that was a joke. They're way to small to ride...
Buford: Not if you scoop up a whole bunch of them! (He scoops up school of seahorses, and rides seahorses) Giddy up!
Phineas: Hey, guys. Look what I found! A door with ancient runes telling us how to open it!
Buford: Forget that! Step aside! (He punches the door, revealing Atlantis)
Phineas: Or that.

(Song: Atlantis)
Male Singers: Atlantis,
Submerged city, you enchant us,
Irving: Click!
Male Singers: Oh Poseidon, please grant us
Entry to the city of Atlantis!
Phineas: Atlantis is a city at the bottom of the sea,
It's soggier now than it used to be,
'Cause it used to be above now it's down below,
All: It's the waterlogg-ed city of Atlantis!
Phineas: Every room and every house has an oceanic view,
If you shoo away a whale or a manatee or two,
There's not a better, wetter place for you to go
All: Than the waterlogg-ed city of Atlantis!
Phineas: Well, the forecast says the humidity is high,
and it's not your kind of place if you wanna stay dry,
You can always have tea with the sea anemone
In the waterlogg-ed city of Atlantis
Everyone but Ferb: In the waterlogg-ed city
In the waterlogg-ed city
In the waterlogg-ed city
In the waterlogg-ed city
In the waterlogg-ed city
In the waterlogg-ed city
In the waterlogg-ed city
Baljeet: And everything is so pretty
Everyone: In the waterlogg-ed city of Atlantis!

Irving: Okay everyone, move closer, while I put my camera on a timer!
Buford: (whispering) I think he's taken this camera thing into a weird level.
Irving: Say cheese! Click!
Baljeet: We are so privileged to be in this strange and beautiful place. To think that the greatest mind in history have been searching for Atlantis for thousands of years.
Buford: Those guys are punks.
Phineas: We should bring this up to the surface for the whole world to see!
Baljeet: Oh, yes. That is a great idea.
Isabella: How do we do it?
Buford: Up! Up!

Candace: (Candace and Linda's Sandcastle falls over) Err! This is the third time it's fallen! I used to be good at this! Now I'm Frank Lloyd Wrong! When did it get so hard?
Girl: (Standing next to her sandcastle) Oh man, this is super simple!
Candace: Argh, I hate this stupid contest. I quit!
Linda: Hon, will you relax? This is supposed to be fun.
Jeremy: Hey, Candace! Hey, Mrs. Flynn-Fletcher!
Candace: Jeremy?! Hi! (She stutters) What brings you to the magnificent shores of Danville?
Jeremy: Well, I'm the judge of the contest this year.
Candace: No way!
Jeremy: Way! I'm excited to see what you two come up with! But you better get started, time's tickin'!
Candace: Mom? Why are you just standing there? Sand castles don't build themselves. Chop chop!

Doofenshmirtz: You see, Perry the Platypus? Your efforts to try to stop me have been fruitless. Fruitless. Y-you like that one? Yeah, that's a good one! Fruitless? Next time you'll "leaf" me alone! Heh heh heh. Yes, Perry teh Platypus, I can be a fun guy. Get it? Fungi? The plural of fungus? Heheh... it's a... Yeah... Anyway, grow my green minions and get him! (He turns on a machine, and sprays the plants, making them thorny, carnivorous, and sentient) Wait, wait not me, not me... Hey, wait, don't be, don't be grab... I gotta turn this off... this has become a thorny situation...
(The plants soon ensnare Doofenshmirtz, and overrun the entire blimp)

Delivery Man: Four weather balloons and helium canisters, for underwater delivery...
Phineas: That's us!
Delivery Man: Aren't you kids a little young to be discovering Atlantis?
Phineas: Yes, yes we are.
Deliver Man: Well, good for you.
Phineas: Alright guys, let's get to work!

(Candace and Linda frantically work on the sandcastle)
Candace: Oh no, Jeremy is almost here!

Doofenshmirtz: Help, Perry the Platypus, help! (The plants squeeze Perry out of his trap) Yes, yes, Perry, you got it! That's it, you're free now, and move over here... wait! Where are you going? Perry the Platyp... (Doofenshmirtz gets slapped by a vine)

Phineas: Okay guys, tie the balloons to the four corners of Atlantis. Looks good, Ferb!
(The balloons inflate, and Atlantis rise up)
All: Wohooo! It's working!

(On the beach)
Jeremy: (Judging a sandcastle) Lookin' good, guys!
Candace: (To Linda) Looks kinda...
Candace: (A piece of their sandcastle falls off) This is horrible! Jeremy's gonna take one look at this, and think that I'm a big losery loser!
Linda: Oh, honey, Jeremy's smart enough to separate your sandcastle from his feelings about you!
Jeremy: Okay, now last, but not least, we have the Flynn-Fletchers...
(Atlantis rises up behind Candace and Linda)
Candace: Well, it's not perfect but... we had fun doing it, so, I give you, our sandcastle.
Jeremy: (looking up, and seeing Atlantis) Holy Moly, Candace!
Candace: I know, I know, it's not great, but we did our best.
Jeremy: Are you kidding? It's amazing! You win, you win! I'm gaining to get your blue ribbon.
Candace: Huh?

Doofenshmirtz: (A vine chomps down on Doofenshmirtz's nose) AHH!
(Perry comes in through the window, with weed-whackers, and proceeds to cut through the plants)

(A few of the thorny plant vines pop the balloons holding up Atlantis, letting Atlantis sink again)
Linda: I have to say, I think Jeremy can't separate his feelings for you from his feelings for this sand castle. He must like you more than you thought...
Candace: Hehe. I know! Let's go get that blue ribbon!

End Credits

Doofenshmirtz: Perry the Platypus, you came back and saved me! Thank you, Perry the Platy... (He begins to breakout) Hey... wha... what's this? I'm having an allergic reaction to these stupid plants! Curse you, inadequate immune system!

Baljeet: What happened?
Isabella: Did anybody see it?
Buford: Why did it go back down?
Ferb: Perhaps the lost city of Atlantis wanted to stay lost.
Irving: At least I got the pictures in my head. Hey! I had my thumb in front of the lens the whole time! Oh, now all I remember is my thumb!