Note: While this is a continuation of "The City of Clay", there's no need to read the previous fic, though it's nice for some context - but this is a new setting, with some new (and some old) science! :D

Iroh II rubbed his eyes. He had a pained expression on his face.

"As much as I would like to say yes, I can't let you go on this mission. We're stretched too thin."

"But we know there's beings out there that need our help! We're certain of where they are this time and-"

"If your ship hadn't malfunctioned we might have had the resources but now…" he sighed. "You know there's a war looming, don't you?"

Korra averted her eyes. While her fleet had been gone on their mission, tensions were rising back on Earth. Despite their best efforts and technologies, there was no denying that resources were running low on their planet, and some government officials had suggested they impose sanctions on their allied species from other galaxies. They wanted to break the space treaty for the sake of new resources. It didn't fly well with a lot of people. Equally, there were people that agreed.

"Politics shouldn't get in the way of this," she mumbled.

Iroh knew she was right. He had devoted his life to helping other species out in the cosmos just like she had. The guilt was gnawing at the back of his mind. "I will speak with the committee again. I'll try to change their minds, but I can't promise anything."

At this, Korra lit up. "Great! Thank you!"

Korra walked down the length of their new ship - General Iroh II had after all talked the committee into agreeing with the mission. They said it was bad luck to name a new ship after an old one, but Korra paid no attention. The only thing she'd ever command would be called the SS Raava and that was the end of that.

She came to the end of the corridor, walking into the repairs workshop, situated at the far end of the ship. On the floor in front of her was a large trapdoor which she heaved open, heading down the steel ladder below the hull.

The innards of this ship sure were less hot than the last one's. The newer model's pipes leaked less steam, and the insulation polymers on the tungsten were better. For once, Korra actually didn't mind the way the underhull felt.

"Asami?" she called out, weaving through the pipes jutting in and out of the walls with sensors all around them.

"Over here!" She called back.

No matter how hard she tried, the Commander would never understand the sheer maze that the engineer worked in. She followed the sound of her voice to find the central power source, something similar to the old SS Raava - a fusion reactor enclosed in a solid lead vat, lined with manual controls if the systems were to fail. Pipes ran out of it through the floor to the engines even further down into the heart of the ship. She found Asami coming up from the hatch at her feet.

"Engines are looking good," the engineer said. "How far out are we?"

Korra lent her a hand as she climbed back up to her level. "We're nearly there. Just wanted to make sure you're alright down here."

"Thanks. Did you read Iroh's report this time?" She wiped a trickle of sweat from her temple with the back of her glove.

Korra rolled her eyes. "Hard not to. I didn't expect Atkova to be quite like that."

Asami chuckled. From what their scans of the planet told them, the atmosphere should contain enough oxygen for them, but it was the ammonia content that worried them most. It was difficult to tell why ammonia was so abundant, but they would get a better idea once they landed.

"Finally a cold planet, though." Korra said. "I was getting tired of the heat on Kythera."

"Cold temperatures aren't my thing but," the engineer smiled, "it's more of a reason to stick together."

The Commander blushed. "Heh, I suppose so." She leaned against the pipes as Asami checked the reactor. She noticed the engineer still had her quartz glove with her, ever since her strange encounter with the Kytherans on the last planet they were on. Korra still didn't really understand how the fourth dimension worked, but only knew that Asami had briefly seen it, and since then has had this strange ability to... reverse entropy? It was something to do with the flow of time. She forgot. It just looked cool, but she still wasn't great at using it.

While they had been back on Earth, they had a couple of days to themselves while the new ship was being readied. As promised, of course, Korra did take Asami to Air Temple Island, showing her around the courtyard. The Avatar herself had never thought much of the beautiful scenery until she sat down with the engineer under the flowering cherry trees. Suddenly, she had felt like the environment was all new to her too.

"This is wonderful," Asami said, looking out at the water around the edge of the island, her back resting against the trunk of the tree. The sunset's colors spread out across the water's surface, creating a beautiful blend of warm reds and cool blues.

Korra picked a cherry blossom out of her girlfriend's hair and chuckled. "Yeah." She smiled as Asami glanced in her direction. "She is."

"Oh, don't start." She averted her gaze, looking back out at the sea, but her cheeks blushed a deep pink. She scooted closer to Korra, leaning against her as the Avatar slid her arm around her. It was a good thing everyone else was inside still celebrating the crew's return.

"It definitely isn't as beautiful as Kythera but at least there's nothing trying to kill us here."

Asami nestled her head onto Korra's shoulder. "The scenery isn't everything," she looked up into the Commander's eyes. She didn't finish her sentence but she understood what she wanted to say. It was Korra's turn to blush as the engineer leaned up and gave her a kiss on the cheek.

The intercom cackled as Bolin's voice came through, bringing Korra back to reality. "We're landing in ten minutes!"

She shook her head, taking in her surroundings like she had just woken up. She looked up at Asami one more time. "Right. I should go!"

The engineer waved her off before taking her seat amongst the pipes and circuitry of the ship, strapping herself in with her seatbelt, watching the readings for anything wrong.

Korra hurried back up to the cockpit, taking her position in the Commander's seat in the middle of the rest of them. Kuvira handled the ship's steering as they approached the planet, while Mako watched the shields and defences to make sure they were ready when they entered the atmosphere. Bolin usually handled transmissions, so was looking out for any warnings that might come in.

The Atkovan solar system was strange. It was barely a "solar" system at all. The windscreen usually automatically darkened to prevent them from blinding themselves when stars came into view, but this time it barely changed. At the center of the orbiting planets was a small, red dwarf, emitting little light. It explained why Atkova was recorded to be so cold.

"2 minutes to atmosphere," Kuvira said, looking over her control panel. The ship's systems were calculating the composition of the atmosphere and the gravitational pull, outputting values for their desired velocity and angle of entry.

Korra looked up from her own readings, seeing the planet approach through the windows. Its atmosphere was clear, with almost no clouds, and as they neared she could just about make out the mountainous, jagged terrain. So much of it though seemed to be covered in water.

Water? But it was so cold. There was no way there was liquid water on the planet, and yet there were vast seas stretching across it.

"30 seconds to atmosphere," Kuvira said.

Korra got on the intercom to Asami. "Status for landing?"

"Clear. No warnings," the engineer's voice rang back.

"Take us down, Kuvira."

The Flight Lieutenant nodded, working the controls of the ship as they descended down towards the planet. "Entering atmosphere. Velocity steady."

"Shields are at 100%," Mako said. He also let out a sigh of relief. After what happened last time, that was nice to see.

They descended down quickly, but in control. The front of the ship glowed with heat from the friction, but the shields barely undertook any damage.

Kuvira steered them down, keeping the ship steady as they touched the ground. Korra looked out at the land around them. It was definitely a huge change from Kythera.

"Woah," she whispered.

They landed in a clearing among the lush wildlife. Plants towered above their ship, with wide leaves and trunks full of climbing vines with colorful flowers, sprouting strange, orange fruit. The ground was littered with smaller, grass-life plants and more scattering vines like ivy, roaming everywhere as though looking for more things to climb on and consume. In the distance, they could make out the water's edge through the foliage, and all of their stems and leaves glistened in the dim light. Although it was supposed to be midday on Atkova, the sky looked like dusk.

"It looks like a rainforest!" Bolin said, leaning forwards in his seat to see better.

Kuvira powered down the engines and unbuckled herself along with the rest of the crew, until Mako drew their attention to something.

"Before we go out, we need to scan."

Everyone groaned. They had been too excited to get out and explore the strange planet that they forgot to check their surroundings first.

The firebender ran the program on his control panel as the crew gathered around him. They watched over his shoulder as they heard Asami walk in too.

As the program finished, it didn't seem to be good news.

"So that's not water," Korra said, looking out the window again. "It's ammonia. All of it." The sparkling seas she saw from the sky wouldn't be as welcoming as they thought.

Asami leaned forward a bit, trying to read through the results a little better. "That explains the toxic air. Ammonia is volatile. Are there enough spacesuits for everyone?"

"Yeah," Korra said.

"Will the ammonia dissolve our skin?" Bolin asked. To be perfectly honest, he wasn't so sure what ammonia was.

"No," Asami answered. "Not in this amount. But the irritation would start to build up over time."

"Right."

"Bolin, did the Atkovans get back to us?" Mako asked.

The earthbender rushed back to his seat and picked up his tablet, hurriedly scrolling through it. "I er… I forgot to check." They held back their eye rolls as he checked. "Yes! Sort of. The message was a little distorted probably because of the landing but they should be expecting us."

"So will they come to get us?" His brother said.

"I… I'm not sure."

"I think they will," Asami pointed out the window. An Atkovan was making their way through the thick foliage, hacking at the vines with a machete.

The crew stared at the being approaching their ship. Although they had met three Atkovans on Kythera, they weren't used to seeing the species healthy. The individuals they met had most of their bodies eaten by their disease and they resorted to building themselves mechanical limbs to try and compensate. The only thing they recognised was their characteristic grey-skinned faces, with short upturned noses and wrinkled expressions, almost always looking angry. It was why they had originally called them the "bat-faces" before learning the name of their planet.

Now, they noticed their natural limbs protruding from their clothing, and for the first time realized their hands and feet were webbed, with fish like fins coming out of their forearms and calves. Their clothes were thin and seemed to be made of some sort of leather. They clung tightly to their torsos and legs, keeping them streamlined.

"They… they swim in the ammonia," Asami thought out loud. The thing she loved most about going to a new planet was the initial learning curve of how life survives, but Atkova was getting more interesting each second.

"If the seas are ammonia," Kuvira said, "where will we get water?"

The crew was silent for a few moments. They had never considered there not being water on a planet with life. All life needed water, surely.

"There must be some," Asami said. She checked her earpiece was working, tapping it once and hearing it beep. "We just have to ask them."

The Atkovan reached the ship and they waited patiently for a sign of the crew.

"Let's get geared up," Korra said, leading them down the corridor. They opened the door to the ship into a buffer room where they were sprayed with disinfectant to avoid contaminating the planet, or vice versa. Their protective equipment was stored away here in lockers within the walls, each tailored to the crews' sizes.

The polymer spacesuits were designed to fit over their undergarments comfortably, protecting themselves and the fabric from the alkaline air outside. The navy colored suits came up to their chins, hugging their necks snuggly so nothing could get in. The helmets came next, made from the same material that went over their head, covering the rest of the exposed skin. The transparent panels were large enough that they could still see each other clearly. On either side, they had the small, circular air filters that would keep the ammonia out of the air they breathed.

"Everyone ready?" Korra asked.

The crew nodded.

With that, she opened the doors and the air hissed with the change in pressure. As they stepped out onto Atkova, the first thing that hit them was the cold air. It didn't take long for them to start shivering, despite the suits' insulation. Although the planet looked like a wet, tropical rainforest, it had the temperature of the South Pole that Korra was used to.

"Earth people?"

They turned and saw the Atkovan approaching cautiously, their language translated by their earpieces as they spoke. From what they remembered, the Atkovans were advanced species too, and they had their own earpieces to do the job backwards for them too.

Korra stepped forward. "Yes. I'm Commander Korra. We've come to help you."

The Atkovan nodded. "We received your message. I am Muu. I was appointed spokesperson of our kind for your arrival. Please, let me take you to our capital and I will introduce you." They took a moment to look at the crew's attire. "You don't tolerate our atmosphere?"

"Ammonia is toxic for us. It will corrode our skin," Korra answered. Despite the air being safe after passing through their filters, it still tasted sour for the crew.

Muu blinked a couple of times. "Ah." They seemed to chuckle. "You must be water-based life. Species like yours rarely like visiting our planet."

The crew looked at each other. They had so many questions but the Atkovan had already started walking.

"I must take you straight to the capital now. Our leaders have been excited to talk to you ever since we got your message." They led the crew through the thick foliage, and as dense as the shrubbery was they couldn't help noticing the lack of other wildlife. They had most probably scared them away when they landed.

"How long have you battled this disease?" Korra asked.

Muu shook their head. "It's hard to tell. We have teams of our best scientists looking into it, but there have been no breakthroughs. All of our laboratories are also based in the capital. I will take you on a tour."

As they neared the edge of the sea, the foliage became scarcer, until they were final able to see the soil under the thick vines. It was jet black, but where the ammonia waves brushed against the shore it had been bleached white.

The crew studied the strange soil for a while, lifting up their boots to look at the black dust that it left on their soles. It almost looked like coal.

Their gazes fell back on the shoreline, and across the flat sea they could see further in the distance than they could in the rainforest. They could see what looked like a port, but there were no ships at all. Instead, submerged pods jutted out of the water, their tops opened up, just the right size for someone to hop inside. There was no one manning the machines, and no one seemed to be coming and going either.

Further along the ammonia's edge, there was a larger port with similar pods, but they were large and heavy looking. The metal looked thick, and they spotted a few robotic arms loading crates into them. A couple of Atkovans watched over the operation, their backs hunched, leaning against the large containers.

As Korra watched the pods in action, She figured it was perhaps faster to travel between settlements by sea than land, with the thick forest and all. It was still strange that they had chosen submarines instead of ships

"This way." Muu led them forwards. "The submersibles will lead us to the capital."

The Atkovan paused on the edge of the pier, gesturing for everyone else to hop in first. The crew hesitated, looking down through the opened hatch and inside one of the pods. It was lined with comfortable seats, and there was probably enough room for all of them.

Mako looked back at the others then back at the pod. He was at the front of the queue and carefully steadied himself as he slid his way down into it. He could just about stand inside the submersible, ducking slightly as he went and took a seat.

Bolin followed, then Kuvira, and finally Asami hopped down as well. Korra took one last look outside before she went in. On the horizon she could just about spot smoke, and the tip of metal buildings over the tall treetops. She wondered whether it was where they were travelling to.

Muu finally joined them last, closing the hatch behind them, sealing it by rotating the circular lever. It made a hissing noise as it locked, and once the Atkovan took their seat, the submersible silent engine started.

The crew looked out the windows anxiously, fully aware that they were surrounded by toxic, hazardous liquid as the pod started to descend into its depths.

The submarine headed deeper and deeper into the sea, and when the light levels dropped low enough its headlights came on. It lit up what seemed to be a whole other world beneath the surface of the ammonia and the crew's eyes widened at the colourful life that lived near the ocean floor.

Plants grew as abundantly here as they did on the surface, covering the bleached white soil with a variety of colours. They housed small, floating creatures with jelly-like bodies that undulated with the ammonia currents, unafraid of the pod as it passed through.

As so many questions cropped up in the crew's minds, the sight of what they were after started to come into view. They very quickly realized they weren't travelling to a land settlement at all.

Large domes appeared through the darkness of the ammonia depths, illuminated brightly with artificial light. Through the glass walls they could see clearly inside, and could make out the bustling activity that went on within the structures. Atkovans came and went, living their sophisticated lifestyle with the aid of robots. As they came closer, the number of domes only increased, each one linked to the other by glass tunnels, forming an enormous interlinked hive. The crew could barely decide where to look. Everywhere there seemed to be something different happening.

"Welcome to our capital, Attara." Muu gestured proudly towards the grand domes as the submarine descended down to a landing pad.

As the crew looked around, trying to get their bearings, the pod was taken into the landing, the doors shutting behind it as the water was drained out. The hatch popped as the seal opened, and Muu let them all out.

"There is negligible ammonia content in our air here," they said. "Your helmets will not be necessary."

As the crew came out of the pod they took their helmets off cautiously, but the sour taste in the air was gone. Muu was right, and they let out a sigh of relief.

"Now come." The Atkovan held their hand out, gesturing for them to head on out and into the dome city. Behind them, the landing shut once again, and the submersible made its way back into the ammonia sea.

"We have much to show you." Muu added, taking the crew down the glass tunnel. Aquatic life floated all around the crew, and they nearly strained their necks trying to see it all at once.

They had been on Atkova for barely a few hours, and it was already nothing like they had expected.