I was summoned to the royal palace by the princess Mermi Mermaid, I only accepted since a gigantic whale and lots of mermen left sometime ago.

Still I don't want to be seen so I enter with invisibility on as some guards come to get me.

We go through the small gate, it seems there's no other entrances even for the mermen, only ones ranging from small to gigantic whales sizes.

Passing through and seeing the upper/bottom and the backside of the gates and dome give me a good idea how they're put together.

The gates are green, 2 km thick and 5km tall, they are placed outisde of the dome.

Both the gate and dome open when the whales need to pass through.

The gate lifts up upwards, fairly fast otherwise of course or it would take too long to to do anything.

The dome opens in a circle, the part that opens up is displaced on the backside then goes back when they need to close it.

I don't know if it's magic but doesn't seem so for either of them, some mechanisms for the dome and pure pulling power from other creatures for the gate, the whales and structure sizes put off your size expectations but the creatures pulling are gigantic crabs and other power fish that are only 30~ meters big.

The megacity is surounded full by a dome going down all the way into the ground, using my radar I see the dome edges down from 1 to 2 km seperating into many plank like shapes and  all crossing each other in a somewhat horizontal path.

I don't see a big space for the huge and gigantic whales either so they don't stay here but the space is big enough for them to rest and sleep.

The smaller whales can fit in the city freely and you see them swimming around.

There's other things down there too, pillars and some big round and square shapes around the area where the dome planks are.

[magical radar] acquired

Oh, I got this so those things must be some sort of magical devices powering the dome, a normal dome can't defend from all the creatures afterall.

I can see magical readings now, I see that the soldier mermen have mana, it's like an energy wave coming from them.

The stronger their mana the more intense and/or bigger it is.

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The facilities nearby also have big readings and the pillars come from there, the mana must be put in the pillars like an electric rod and give the magical devices power.

I pick up magic from the gate and dome too, [appraisal]

gate - algae, zooplankton and whale carcass

dome - magic chalk limestone

WOW it's so simple that it's amazing.

The gate's green color is due to the algae and the dome's clearness must due to refining the limestone.

It also explains how they got so much resource but how you can get limestone in the ocean

[appraisal] magic chalk limestone - phytoplankton algea, zooplankton carcasses

The algea becomes the foundation and the carasses turn into calcium hardenining it further.

With just this method you can make everything you need without having to dig and mine the ground and earth which is very risky if you're in the ocean since you never know what will happen if you displace so much mass - monsters hiding spots, dangerous zones breaking forth, ocean shitfs.

They still have to be mining rare areas I assume but it's not their main way of producing their materials.

The white pillars are made from oxygen and silicon minerals so some sort of quarts, it conducts the magic well and i guess it releases oxygen? the dome is closes after all

They should have circulation somehow, maybe the gates opening and closing is enough to keep the city flowing.

The more I see and the houses and facilities are are made from these too.

There's large areas for processing everywhere, this might not be a military city but a production city.

The resources they harvest are brought here and divided, distributed and more processes added like that factory over there which is adding coating of other minerals to things and infusing them with fire or magic.

The supply whales must be for this reason, they are supplying areas with food to help the plants and creatures do their thing and reap the benefits later.

It's ocean agriculture.

It will take a while to get the palace since the city is so huge so the mermen and me get on a huge fish and they cast magic to stay on.

The fish is fast and we arrive in 20, this is like a taxi service the citizens must use these too.