Physical modeling suggests that structures should be where no light comes from above. There are objects around. Static. Likely of no mission-related interest.

[NULL LOGIC EXCEPTION]: There is, in point of fact, no established mission objective.

Darkness to her sides. Darkness below, and above. She calls to the four cardinals and the two more that are just for her, and hears no answer, no respite. A bubble of air trapped beneath plating squirms its way out down a channel and she kicks off, following it at a safe distance.

Oriented in space, the body spares no expense. The water is heavy, constricting, but not turbulent enough to matter. The fluid is heavy, but the metal is heavier.

There's enough light up here to see where light isn't. A partial map is constructed. 

Scanning… A partial structure revealed. An exit to propel herself towards.

These fingers will dig into concrete and rebar just as well underwater as they would over it. Just as well unseen as in the light overhead; it's just a question of reaching around a bit.

Grasping in the darkness at angles her proprioception insists should lead somewhere, and finally finding purchase. Pulling herself along as her other hand casts about she starts swimming upward, leaving the ocean (?) floor behind.

It requires a bit of finesse, but the involved models are simple. Stab fingers, pull, remove, kick. The density of the water actually provides some much-appreciated error room, crushing pressure aside.

Up, up, up.

The light approaches. Reaching the surface.

Lungs inflate for the first time in what feels like ages as her head breaks the surface, the drip and trickle of water running off dull matte plating, eyes scanning the horizon for anything familiar. The city around her is sunken, but here in what used to be streets turned to canals, life goes on. She can see plants overgrown on upper floors and balconies, she can see the clouds seem lighter and less dense... But nothing about this place is familiar. She needs information.

This place was likely abandoned a long time ago. Her best bet is to find some kind of comms infrastructure that she can try and transmit with, and, perhaps along with it, some sort of database. No outstanding radio signals yet, from the horizon or from the skies. Where would she find such a thing?

She tries to remember the layout of cities, scanning the horizon for any hint of high towers left standing. Comms infrastructure and data servers were often kept in high places, less prone to flooding. If she can find an old uplink station, even if the equipment is damaged, she may be able to rig something to boost a distress call and access archives. With a destination in mind she begins heading towards the highest points left in the city, hoping infrastructure largely followed the rules of the past.

Looking at it, aside from all the water, the city doesn't seem all that foreign. A familiar snapshot, multiply disfigured in regularly distributed fashion. Everything is concrete, cement, glass, and metal, same as it ever was, though the paint is ruined, much of the glass is broken, concrete tumbled, cables tangled and warped by fallen structures... a familiar urban landscape, after geologic post-processing.

How long has it been?

To the heights, then. Something like a broadcast tower, phallic and peppered with doodads and dishes, stands between the buildings. Almost certainly ruined, but the scraps and the tall building close to it might have something to offer.

Movement here is non-trivial for a thing as heavy as this mobile infantry platform. Traversal by excellence is doable, if treacherous, but a more permanent, reliable solution might be best. 

She swims towards the tower, ascending fallen rubble and pulling herself up onto plantscum-coated platforms and balconies, scanning the horizon and keeping an eye out for hostiles, though so far the city seems empty. Finally climbing the last few meters of ladder and hauling herself up over the edge of the tower platform, she takes in the vista - so much of the city is submerged, but life goes on. Plants have overtaken many of the buildings, she imagines watercraft might move along what were once roads. But no signs of human habitation.

There is a ladder, though it's rusted and worn and even at its prime might not have sustained this unit. The dishes are mostly worn and rusted, too, at least decades of humid decay. But above it all is something stranger--not intact, not... functional-looking, or emitting any signal perceived on sensors, but almost certainly more recent, less covered in the fuzzy red and green hues that characterize most of the metal on the tower. It's simultaneously blocky and chaotic, flat covered panels connected by black wires, crossed in spikes and arrays that might be antennas. A single dish stands above the assembly, facing the sky, while the rest juts out in all directions. A hack job, but recent. Within the decade.

She approaches the hack job assembly carefully, scanning for any signs of activity or hostiles. So there was someone here, recently - possibly still are. She reaches out to gently brush fingertips over the wires and panels, testing connections, trying to figure out the purpose of this construct. It seems designed to transmit and receive, but the architecture is unfamiliar. Still, she tries powering it up, amplifying the signal to send out a distress call on all frequencies, hoping someone, anyone might respond. "This is Arisa requesting assistance, does anyone copy?"

The composition of the device isn't so much arcane as it is schizophrenic. All the parts are identifiable, upon scrutiny--improvised radio and computer components--but it was clearly not made with a design in mind. Or, rather, not from the start: they kept adding bits on, trying to make it stronger, add functionality, store information. Some bits seem to be powered by a modified standard fusion battery (long-burst), others by some kind of air pressure mechanism. There are solar panels, and wires connecting the whole thing to something at the very top of the tower, probably more solar panels. All this is to say that it is not an easy machine to fuck around with, for all that it was created essentially by an iterative process of fucking around. There's even a camera there. Hello.

But this unit is a very sophisticated machine, and has plenty of internal power besides. Connectors emerge from the wrist and splice into wires, interface probes expand their electromagnetic effectors. It is not fully equipped for this kind of work, but this isn't a fundamentally complex task, only a convoluted application of simple capabilities.

And fuck around it does--test pulses and direct manipulation of transmitter array systems make some sense of the unclear and ascertain the obvious: shove some power in, scream into airspace, maybe receive something. It should work. Ignoring the digital-analog noise the convoluted subsystems this thing is made out of are firing back, the unit communes with the transmitter array, and shrieks analog.

Strange digital signals respond, within the machine. Origin unclear. And temperature increases somewhat.

She frowns at the temperature increase, wary of overloading the jury-rigged system. The digital signals are concerning as well, this thing seems to have awakened in a way, though the purpose and intelligence behind it is unclear. She tries again, "This is Arisa requesting assistance, I have accessed an improvised transmitter in a sunken city. Does anyone copy?" The system seems barely held together, if she can get through to someone before it fails or decides she is a threat that would be ideal. She reaches out to try and stabilize power flow so she has time to work, confused by the strange responses. What had they built here?

A highly-compressed hundred years of progress in signal processing and data analysis goes into deciphering the data coming from the assembly, but if this unit was not made for electric maintenance, its hacking subroutines certainly were not made to deal with... whatever this is. Parallel analysis suggests the digital signals are genuinely being transmitted in 12 bits. Most of them. Some kind of rudimentary computer built 'from scratch'? Unclear. Nevertheless, an electrical system is an electrical system, and there are some certainties; disconnect the wires and energy will not flow. These power sources are no longer necessary.

An anomaly. Power flowing through the clearly broken fusion battery, as reported by vision. Snip snip. Temperature continues to- oh.

[DANGER] - [ASSESS PHYSICAL THREAT]

[FAST MODE]

The reactor sings. Clock rates shoot up into theoretical limits. Emergency cooling latches prepare to release.

The damaged fusion cell, now cut from the power network, makes a noise. Some kind of orange spark flies from it. Detonation is highly plausible. The cell is clearly modified. It may be less dangerous than expected, or far more. Expected shrapnel could cause some damage to peripheral systems, such as interfacing, communication, locomotion, and armament. The situation is uncertain. Said systems may be vital in the medium to long term.

And this unit has made quite a lot of noise. And perhaps soon literally so.

Eyes widen at the realization of her mistake, hurriedly yanking interfaces free of the jury-rigged transmitter as she scrambles away, leaping from the tower and hitting the water below just as a BOOM rocks the sky and bits of fused metal rain down. She dives deep, rushing away from the tower as fast as she can propel herself until her internal warnings calm, slowly ascending once more to break the surface and look back at her handiwork.