"That's actually my first time going on a boat," Maëva noticed, looking over the magical rail and into the sea below. "I thought I would be seasick."

Her sentence was punctuated by the sound of Sunset throwing up in the water.

"How can you vomit...?" Twydra wondered in disbelief. "We don't even feel anything below our neck, how is the stomach sending things to you?"

"I don't want to think about it..." Sunset answered with a pale green face, on the verge of throwing up again. "I wasn't even sick the last time I was on a boat, I don't get it..."

"Don't worry, we'll be there soon," Twydra reassured.

"Wha' be dis weakness ye be showin', camarade!?" Flurry suddenly shouted from behind the helm, wearing her most outlandishly cliché pirate costume, tricorn, eye patch and everything. She had even painted one of her legs to look like wood. "Dis ain't how adventurers shall look like!"

"You can tell she doesn't go out very often," Maëva said to the others in a half-amused, half-impressed tone.

"Worlds are collapsing..." Twydra muttered, slightly offended.

"Let her have this," Cozy sighed, a pissed resignation painted all over her face, as she was standing next to them, in a marine officer outfit. She had no say in wearing it.

They were sailing into the sea, Flurry using her magic as a sonar to locate the sunken island they had seen on the map.

"How much magic does she even have?" Maëva wondered. "You've told me alicorns have more than unicorns, but I have trouble visualizing it."

"She could hold the boat for one week, probably, if she wanted to," Cozy explained in a monotonous voice, still feeling uncomfortable in her suit, even if she was doing it for her friend. "The only time I saw her exhausted, magically speaking, was when she fought Twilight for a day, just to train."

"And Twilight is the Element of Magic, right?" Maëva said, trying to remember what she had been told. "So like, a representation of magic itself. And Flurry went toe-to-toe with her for one day, I see."

Cozy nodded with a little smile, somewhat happy that Maëva was understanding. But her smile vanished when she heard a repeating sound. Flurry was storming her hoof on the floor, bobbing her head in rhythm.

"Ah, that's my cue, sorry," the pegasus said, suddenly flying up to the alicorn.

"Huh?" Maëva and Twydra both said.

To their surprise, Cozy and Flurry joined together and began to sing a sea shanty. And, despite the poor attitude the pegasus seemed to have up until now, she smiled the whole way through the song with her friend. A song about their bond, and their past.

Maëva glanced, with questions in her eyes, at Sunset, who was still feeling sick but looked back at her in a way that meant "Yeah, that tends to happen around here, don't worry". Either way, the song was enjoyable.

Flurry's sonar detected the remnant of the island a few minutes later when she exclaimed "We found our target, mates! Drop the anchor!"

"Why don't you just use your m-" Maëva began.

"I said drop the anchor!" Flurry cut with authority. "Be ye formin' a mutiny against yer cap'n?"

Twydra rolled her eyes, but Maëva complied and reached for the capstan, pulling on the lever to let the anchor loose. The sound of the magical chains echoed for a bit, before it stopped, and it took a little bit longer for the boat to do the same.

"Alright!" Flurry said, suddenly abandoning her pirate accent, heading down to the main deck. "Let's go for some scuba-diving!"

"Who wants to have a bet about hydra buoyancy?" Cozy proposed, getting rid of her clothes.

"What do you mean?" Maëva asked, uncertain about the meaning of the word.

"Do you think your body floats or sinks?" the pegasus elaborated with a bright smile.

"Sink," Twydra almost cut. "There's no way a body like that can float, unless we are able to take a really deep breath."

"Let's try it out!" Flurry happily said, her horn glowing. "First, a mask for everyone!"

A spherical bubble appeared around every head, including Cozy's and Flurry's, and they all began to speak with a weird muffled voice.

"Great," Sunset congratulated. "How do we head down, now?"

Flurry looked at her with a happy smile. In the blink of an eye, a slight worry appeared on Sunset's face, and on Twydra's and Maëva's as well. Their fear was doubly confirmed when, first, Cozy deployed her wings half a second later and, secondly, when the boat disappeared entirely.

The hydra crashed into the water and found that, indeed, their body was sinking. After a little panic, they all calmed down and looked at each other. Maëva peddled her feet in the water, but didn't feel like it made any difference in their trajectory towards the bottom.

It only stopped when Flurry and Cozy joined them under the water, Flurry holding the hydra with her magic to prevent them from sinking too quickly.

Cozy seemed to talk, but they could barely hear her, as Flurry gestured to indicate that, pointing her own ear. Cozy rolled her eyes and extended her hooves towards her friend, as if to say "You're kidding me!". At least, that's what Maëva understood from this exchange, but Flurry seemed to get more out of it, her face enlightening as she adjusted something in her spell and spoke:

"Test," all suddenly heard in their own little magical bubble, as if she was screaming. "Is this working?"

"Too loud, Flurry," Sunset winced, making everyone else cringe as well.

Flurry's magic turned around her horn turned a bit, like a knob, and tried again with a much lower volume:

"Now? Is it good?"

"It's fine," Twydra said with a sigh of relief.

"Sounds like a radio," Maëva thought out loud.

"That way we can talk," Cozy followed. "Now, how deep is that island?"

"About four hundred meters deep," Flurry said.

"You'll need to protect us from the pressure," Twydra warned.

"Yeah, right, I'll do that now."

The bubble on their heads spread from the base to cover their whole body in a thin magical layer, glowing in yellow light.

"Hope that won't attract some sharks or something," Sunset worried. "Let's head down."

The two ponies swam downwards, while the hydra was simply released from the alicorn's grip and began to sink.

"Do you have, like, giant monsters in your seas?" Maëva asked, curious.

"What do you mean by that?" Sunset said, arching an eyebrow.

"I don't know, krakens, leviathans, mythological things and whatnot. You have pegasi, hydras and unicorns, so I'm just curious."

"We have legends," Flurry answered, her horn lighting the way through the obscurity that began to encircle them. "And here, that means there's a chance they might exist. But I don't recall anyone ever saying they saw a sea monster, aside from sea dragons and alike."

"Huh..." Maëva said, pondering this possibility. "Are they civilized?"

"They can talk, if that's what you're asking," Flurry replied with a smile, looking towards the bottom.

Light from the surface was almost gone by now, leaving them surrounded by nothing but darkness, cold water and the occasional sound, coming from some far away sea creature. Otherwise, things were quiet.

Maëva felt uneasy, going down without any control, sinking in the shadows. She couldn't see one meter below her feet, she didn't even know if there was something to see. No fishes were around. From the corner of her eyes, she noticed Cozy Glow progressively swimming closer to Flurry Heart. Was she scared?

"That's deep..." Sunset whispered with a fascinated voice.

"Not that much," Cozy replied, glancing at them. "Oh, you have to be kidding me."

All followed her eyes, seeing Twydra shaking and staring at the void with a quivering breath, terrified.

"Hey, hey, Twilight," Sunset called, bringing her head in front of hers. "It's fine, okay? We have magic."

She barely listened nor saw her, saying in between her breathes:

"It's dark... It's so cold..."

Flurry rushed to her as well, waiving a hoof in front of her.

"Twi? Are you okay?"

"Warm her up and get more light," Cozy advised.

Her friend obliged without question, their surroundings becoming enlightened in her magic, while the hydra felt the coating around them becoming warmer.

It somewhat seemed to work, as Twydra's eyes focused on the alicorn in front of her, realizing where she was and what was happening.

"S-Sorry," she said, shaking her head.

"It's fine," Flurry reassured with a kind smile. "The depth can be frightening."

"Usually it's not, for someone who heard the call of darkness once already," Cozy innocently added, resuming her diving.

Only Maëva really paid attention to what she just said, Sunset and Flurry too busy checking on Twydra. The third head blinked a few times, taking in a deep breath, before saying:

"I'm good. Sorry about that."

"Alright, great," Flurry said, relieved. "We're almost there."

As she said that, below them, the seabed appeared. Getting closer and closer, white brownish plains of wet soil and sediments

With a surprising grace, the hydra landed in a slow puff of smoke and sand, which spread around them, before settling again. They all looked around, as Flurry was still pushing her horn bright, scaring the nearby confused crabs, but nothing really jumped out.

"Now what?" Maëva said. "We search around?"

"Yeah, I guess," Sunset nodded.

The alicorn took the lead, and they all followed, Cozy swimming with her wings, while the hydra was just walking on the seabed. And Maëva contemplated, for the first time, the bottom of the ocean.

The soil was strewed with more rocky terrain here and there, signs of this land once being emerged in the form of old rotten and withered roots, but also...

"A paved road...?" Flurry noticed at the same time, hovering closer to the ground, intrigued by the ancient structure.

Small randomly shaped rocks, definitely assembled in a straight and wide line. Though the work seemed way more crude than the ancient city they had visited, indicating the place was probably less important. But they had found a trail.

The small group followed it with care and curiosity, spotting little things they supposed to be milestones, with small indiscernible inscriptions faded by time and erosion. Until, suddenly, Cozy softly said:

"There's a town..."

All the others had to squint to realize that, indeed, structures were visible in the distance. Guided by Flurry's light, they entered the town. A village of ancient stylized but modest houses, made out of polished stones. It was more of a little settlement than anything, they could only count six houses and what seemed to be a temple, towering over the rest of the ruins.

The edifice had an Ancient Greece vibe to it, with tall columns made of stone, but the roof was a half-sphere. Maëva's eyes were drawn to it, and she quickly picked up that something was off with the columns. Or rather, what was in-between them.

"Oh wow, the spell lasted that long...?" Sunset noticed too, impressed.

Indeed, a thin magical membrane was separating the inside of the temple from the rest of the world. And behind it laid a different obscurity, one that Flurry's light easily pierced.

"There's air," Maëva realized.

The group headed for that strange place, the two ponies sliding in between the columns, while Maëva and the rest had to find the largest gap possible and squeeze their body through it. It took a bit of help from Flurry's magic, but the hydra managed to pass.

The temple was only one large room, surrounding some kind of tall obelisk. The first things that caught Maëva's eyes were the six silvery rectangles disposed in a hexagon all around the monument, one of them broken. The second things that caught her attention were the numerous bones laying on the floor, from fishes, but also four of them who were from pony-like creatures. Except they had long tail-bones.

"Wow, that's creepy," Flurry admitted, nudging the bones with one hoof. "You think those fishes just went through the barrier without realizing and choked in the air?"

"Why are there bodies here...?" Sunset wondered, looking at the strange remains of those strange ponies. "What are they even?"

"Thornies," Cozy bluntly said, looking at one of them. "At least, that's what I call them. Never heard an official name."

"For Celestia's sake, how many things do you know, exactly!?" Sunset growled.

"Not much," the pegasus distractedly replied, glancing at the silvery rectangles. "At least, nothing relevant here. And we're all about to learn a lot more."

As she said that, a dim red light suddenly spread in the room. They all turned around, only to see Twydra's head willingly poking against a small stone engraved with runes, lying up against one of the columns. A voice came out, different from the one they had heard in the ruins up north.

"Can't believe I have to use this spell. Sullirian's ideas are as crazy and foreseeing as ever. That's probably why he left this place early. If you listen to this, you're a little bastard for bringing us all into your rebellion, even if we all believe your calculations are correct."

The voice sounded angry but resigned, and seemed to belong to an old mare. She kept on speaking with her bitter tone:

"But if it isn't you, I suppose I should help those who need it. The Cleaners are above us, they made the island sink anyway, there's nothing more we can do. They're waiting for us, Nagalili already went out and was almost immediately thrown into the void. So, if you're not Sullirian and you managed to get here, you're probably aware the Four Counsels are denying or hiding the truth. Here's what you need to know: The worlds are unstable. We've put the pillars that keep them up and next to ours, but they're not perfect. The pillars might crack and fall, collapse, and bring down the worlds with them. Sullirian is working on a solution, he's probably at his hideout at the Shadowy Hills as I speak-"

The voice suddenly got interrupted by another one, coming from further away, mumbling:

"This is stupid, I'm taking one of the portals."

"As you wish," the first voice simply said, before resuming her story. "There's no one beyond the void. No one conscious, at least. We made our neighbors, but the threads are still from us. If anything would happen to them, the pillars would collapse, one by one. Who knows what's down there, in the void. And when their inertia runs out, they'll be gone... And-"

The voice stopped again, but this time no other sound followed. The rune ceased to glow, spreading a bit of confusion in the listeners.

"Either the rest of the message got corrupted by time," Flurry said. "Or that magic can't hold too much information. Either way, I think that's it."

"What was this all about...?" Sunset whispered, squinting, trying to make sense of what they had heard.

Twydra glanced at Cozy, who was also frowning, but not in a confused way.

"You got something from that, didn't you?" the third head commented with a disparaging tone.

"It just confirmed what I thought..." Cozy replied, still thoughtful. "Some of them knew something was wrong, but the others didn't listen and hunted them for that. That Sullirian guy is, without a doubt, the one you've heard in the ruins of the Empire. And he tried to do something about it."

"Well, he wasn't very successful," Sunset commented, raising her eyebrows, unimpressed. "Otherwise, we wouldn't be here."

"Or his solution only worked for a time," Twydra nuanced, still wary of the pegasus. "Maybe something broke his solution."

Cozy's eyes slowly went down, her expression switching ever so slightly from thinking to atrociously realizing.

"So, people got trapped here by those Cleaners," Flurry summed up. "Those things made the island sink, and the, err, Thornies you said? They got stuck here, after raising that protection around the temple. And one of them left by a portal."

She turned to the six mirrors, happily supposing:

"If we go by this logic, those things are portals. They even look functioning, aside from the broken one."

"Do you think we could take them?" Maëva wondered. "Or am I going to grow another head?"

"Hmmm..." Flurry thought, circling the pillar with the five still-working mirrors. "I wish auntie was here."

"What good would taking them even bring?" Twydra thought out loud.

"If we see how things are going, maybe we can figure out a solution," Sunset said, Flurry agreeing. "We've studied magic, maybe seeing the problem up close could help."

"Or you'd end up in a collapsing world, with no way of returning somewhere safe, with no magic," Cozy proposed, with a tone indicating she thought that was stupid idea.

"Pff, as long as we warn auntie before, things will be fine," the young alicorn said, waiving a nonchalant hoof.

Cozy stayed serious, more than before even, but her eyes filled with a touch of begging as she looked at her friend.

"Do not force me to follow you there..." she said, her tone grave yet not commanding.

"You're not forced to," Flurry pointed out, her ego speaking. "If you want to stay there, or go back up, I'll give you the necessary bubble for that, while we explore solutions."

She stared at her with smug eyes, as if she was expecting the pegasus to yield. Yet, Cozy's gaze didn't change one bit, and they stayed like that for a moment.

Sunset was quicker to understand what was happening, though she didn't really believe it, but Maëva was a close second. Cozy wasn't saying Flurry would force her in some physical or rhetorical way. She was telling her that, if Flurry went in, she would have to follow her, despite knowing fully how bad of an idea that would be. She would not abandon her, even if the princess was to jump head first into her downfall.

Twydra didn't understand what that eye-battle meant.

The young alicorn finally looked away, annoyed and hissing at a low voice:

"Fine, fine! I get it, things are serious... I swear you're worse than my mom, sometimes."

Cozy let out a sigh of relief, before turning to the hydra.

"Alright, touch the portals now."

"Huh?" the three heads said, looking at the pegasus.

"Maybe there's someone stuck in there too," she explained very seriously. "We can't abandon anyone like that. I'm not asking you to go through the portal or anything, just touch it."

"Sounds awfully dangerous," Twydra commented, while Flurry pouted.

"It doesn't suck people in," Sunset reassured, seeing where Cozy was coming from.

Maëva also agreed to that thought process, even if she had joked earlier on about gaining a new head. Having someone lost in-between the worlds was too great a risk, especially if the portals were to break.

"If it tries to suck you in, I'll stop it," Flurry said, still pissy but ready to help. "I'll grab you with my magic."

"Thanks," Maëva said, even if she didn't think this would be necessary.

She turned to the mirrors, Sunset confident and Twydra not so much.

"First one!" Maëva said to give herself some courage.

She tapped the tip of her tail on the top of the borderless silvery surface, as she had done to free Sunset and Twydra from the Crystal Empire's portal.

A little silence installed itself in the atmosphere, everyone expecting something. But nothing came.

"Check, I guess?" Maëva said, moving a bit to be in front of the second portal.

She tapped it as well, this time interpreting the lack of response way faster and moving to the next one, passing by the broken portal, and tapping the third mirror.

"It's going to be on the last one, isn't it?" Sunset sighed, before a sudden flash of light blinded her. "Aaah!"

Twydra and Maëva had to turn away, the middle head shouting with a victorious tone:

"Aha!"

The glow from the mirror forced everyone to close their eyes, but Maëva felt the energy flowing through her tail, just like the other time.

A puff of silvery smoke erupted from the mirror, as the light died out, and coughing was heard.

"For crying out loud, those portals!" a deformed hydra masculine voice said. "What a collapsing load of bollocks!"

Maëva froze, as the other heads were turning back to look at the newest arrival, on the leftmost side of the body, next to Sunset.

"Hello there," she greeted her new neighbor.

"What is t-AAAAAAAH!"

The new head jumped back, opening wide scared eyes, trying to recoil as far as he could.

"Yeah, something like that," Sunset nodded. "Sorry to scare you."

"There's no point in trying to run, you're attached to us," Twydra informed.

The newcomer looked at them with terror, then at himself, seeing the long neck linking him to the others, confused.

"What in the name of Geuzav is that!?"

"What in the what?" Twydra said, arching an eyebrow.

"Where are my arms!?"

"You don't have them anymore," Sunset sighed empathically. "It's a long story, but please calm down."

"W-Why can't I move!?"

"Only Maëva can move it," Sunset explained, nodding towards the main head. "I'm Sunset Shimmer, and the farthest one, that's Twilight Sparkle. But we call her Twydra. Er, long story too."

But the fourth head was barely listening. Instead, he was looking at Maëva with a slight frown, and she was staring back, eyes wide open.

"Maëva...?" he repeated.

"Enzo...?" she asked in disbelief.

Author's Note

There's something off in my writing in this whole fic I feel. I'm under the impression that I'll have to go back and fix almost everything. I don't know. It's the most "first-drafty" first draft fic I've done in a long time. (I re-read though. But massive changes are rare)
Also feel like I'm really not using the hydra concept to its full potential and more as a gimmick.
Also, one day I'll write the song. One day.
I guess the pirate thing was also a reference to the album Aetheria by Forest Rain (totally didn't participate in the choirs for the first song)