SUPERBAT

Underwater

Keep in mind this isn't cannon in the least, I made it all up. Even the plants. And trench. The under-water cave city.
And these [] mean in a language other than English in which the charchter whos P.O.V it is can understand. For example if it was Aquamans P.O.V and Batman was trying to learn the Quichan language he could hear '[hi, I'm] Batman' and only Batman would be in English.
Supermans P.O.V

I carried Bruce (who wasn't wearing his cape because of drag) as we followed Aquaman down into a deep underwater trench. Bruce had explained that he would be fine with his re-breather and his suit which was designed to reduce pressure. He was originally coming in a submarine but there wasn't enough space in the trench, and because of how fast Aquaman could swim and my ability to fly he would of gotten left behind if he didn't hold onto me. At the start he sat on my arm like you would sit on some stairs but we had gotten attacked and he had wrapped his arms around my neck so he didn't go flying.

We swam down and I saw Bruce look around at all the algae and underwater plants in fascination. They were a bright blue-green colour and they stood out amongst the rocky walls and ceilings (the floor randomly dropped out sometimes) while giving the only light down here (Aquaman had mentioned this and I had went to the sun to 'charge' before diving down here, I should be able to be fine till the end of the day when my powers would start weakening and stopping). Bruce kept at least one arm wrapped around my neck while reaching out to touch the plants and occasionally take samples, I could almost hear his mind running at a thousand miles per hour to decide how to replicate these conditions in an aquarium.

We were going a city located in an underwater cave, it was protected with miles upon miles of tunnels that took almost a whole day at a normal human pace and when you knew where you're going. Luckily, Aquaman was here with us to show the way, and we weren't normal humans.

After swimming for two hours we arrived at a small hollowed out area "Welcome to the deepest temple of Posidon." Aquaman said, both me and Bruce looked around. There was a statue of Posidon holding his trident and the walls were carved, but before I could see more Aquaman started swimming again "We aren't there yet!" he called.

...

"We're almost there." Aquaman said to me, I nodded and and tapped Bruce to wake him up,
"Did you tape my re-breather to my mouth?" he asked indignantly as he pulled the tape off
"It wouldn't stay it." I gave him a shrug
"Thanks for carrying me here." he said, and he pulled on arm off my neck to stretch. After about three hours of doing/seeing the same thing and I had told Bruce it was fine to relax and he had fallen asleep, I had had to hold his arms in place around my neck as he slept on my back but I didn't mind.

So finally, after six hours of swimming, we were there.

Bruce let go of me as both me and Aquaman slowed down to enter the city, the guards saw Aquaman and let us through.
"Woah." I couldn't help myself but say

Batmans P.O.V

"Welcome to the second lost city, Quichan." Aquaman said. I switched my cowls lenses to see in the dark.

There were sea-snakes acting like glow worms that seemed to be nesting and lighting up on the walls of this giant dome of open water in the earths rock, there were stands of seaweed with bioluminescent pods at their ends that lit up the city.

The people (Quichans) seemed to be more obviously ocean creatures than Aquaman and those of his city, they had gills, their eyes flashed in the lights like cats and if I had to guess they could see in the dark better as well because not all of the city was perfectly lit up and they were swimming out and in of the some tunnels with no obvious sorce of light. They had spikes with membranes connecting them coming out from their ears and also webbed fingers and flipper-like feet. The Quichans were smaller than the average human, not by a lot but still obviously. It must be the denser water, they'd need stronger possibly bigger bones and there would be less room for just random flesh with everything more sandwiched together. A guard wating inside said something I didn't understand, Aquaman said something back then turned to us
"We will take you to your rooms in the palace." he translated.
"Tell them we thank their King-"
"Queen." I cut in
"-Queen for the hospitality and hope the peace treaty ends favourably." Kal asked, Aquaman nodded and turned to the guard to speak in the other language

By the time we got through the city and to the castle, with my surrounds and some help from Aquaman I had a translator (when the Quinchans said things what they meant came up in a text box on my lenses) and had some notes about language and body language gaps and possibly disastrous differences.
"Kal." I said after watching a street fight and some people who seemed happy "I don't think smiling is a think here, their was of smiling seems to be moving their ears higher and more fowards. Smiling might be mistaken for baring your teeth in hostility, so don't smile." I explained,
"Got it Batman." Kal said. I noticed one of the royal guards (who had taken us from the city guards) looking at us and bumped Aquamans shoulder
"Can you explain that we aren't trying to talk behind their back we just don't know the language, and that I have a translator in my helemet so I can understand what their saying." I said, he nodded and said
"[Batman and Superman aren't trying to talk behind your backs, they just don't know the language, Batman has however made translator his my helemet so he can understand what you're saying and translate to Superman]." Aquaman said to the royal guards and most of them changed to looks of understanding.
"[I apologise]." said the guard who has been glaring "[I assumed you meant to dissrespect our culture, and by extension us and our queen]." he explained, "[We have the same nodding and shaking of head system as you if that helps resond]." he said again and I nodded.
"What'd he say?" Kal asked
"He said 'I apologise. I assumed you meant to dissrespect our culture, and by extension us and our queen. We have the same nodding and shsaking of head system as you if that helps resond.'" I translated for Kal, "I'll build you a translator once we get back to the surface."
"Thanks." Kal said "I feel like dead weight."
"You aren't. For one thing you are one of the most well known heros and will be a great ambassador for earth and for another I never would've got here if it wasn't for you- don't even suggest me riding on Aquaman." I said.

Just then we came into the throne room. Aquaman bowed,
"[Greeting Queen Amaro. I am Aquaman, king of Alantas. This is Superman," he gestured to Kal "One of the surfaces mightest heros from the planet Krypton, with many powers. And this is Batman," he gestured to me "He is the other hero sent to help and is widely considered the worlds greatest detective. While he has no powers he makes up for it mentally, as has already been proven by the fact that within the 10 minutes we've been here he has already built an almost perfectly working translator. Unfortunitely neither of them can speak ??? but batman can translate to Superman and I can speak for them]." Aquaman said, while he spoke I whispered to Kal the whole thing.
"[Thank you for coming so soon even when you didn't know we existed until we reached out. I will explain to you the grave circumstances of your vist and any payment you may request in 13 hours," a Quichan day "But until then we will house you, we have some large untouched air pockets in the ceiling, while we cannot survive in air it may be helpful to you Batman and Superman. Do you want to be shown to your rooms]?" Queen Amaro said and I translated to Kal again,
"We thank the Queen for her kindness and assure her we will help regardless of what she has to offer. I'll go to the air pockets." I told Aquaman
"I'll go with the guard to the room." Kal said,
"[We thank you for your kindness and we will help regardless of what Quichan has to offer. Me and Superman ask to be shown to our rooms and Batman will go to the air pockets, I have no douts he'll find his way]." Aquaman said and I translated to Kal, the Queen visably relaxed when Aquaman said we weren't doing this for a reward.
"[We thank you for your kindness, unfortunately we don't have much to give, we sustain ourselves and little more. Guards]." Queen Amaro said and again I translated to Kal.

Aquaman and Kal followed the guards and I swam out the window/door (there was one in almost every room for making moving easier) and up to an air pocket. I grabbed onto the rock and pulled myself out of the water and took the re-breather out with a gasp. The air was damp and smelt like water and rocks, but it was still fresh air, I breathed it an out slowly and clicked on a flash light just as I saw a Quichan child swim up to me in the water.

"[Hello]?" she asked, I dunked myself in the water tried to repeat what she said before coming up for air and grabbing my re-breather, she giggled at my attempt. "[Hello]." she repeated and I took a deep breathe and pulled out the re-breather to say
"[Hello]." back, before I put my re-breather back in
"[What is the thing you're eating]?" the child asked, I pulled up the recordings of some previous conversations (either had or overheard) and replied
"[Not eating, it is...]" I trailed off as I searched for any words to exlpain "[It makes air so I survive]."
"[Why do you talk strangely]?" she asked as I put in the re-breather and took another breath.
"[I not speak your language]." I explained "[I am guest]." I said and she giggled "[Show me to speak]?" I asked, it was clear I was asking her to teach me how to speak Quichan. She nodded.