Day Five: Unsicherwaffenfabrik "Seeharnisch" . This week: 7 variations on the Kleinpanzer frame. Number five is a deep sea military assault exoskeleton. . Manufactured by Unsicherwaffenfabrik (GmbH) for the military of the Terran Concordat for deep ocean combat operations, including, but not limited to, the storming of secure ocean floor command posts and research facilities. It's also quite capable as a sub-hunter, assuming the submarine is for some reason forced to stay put in once place, since while the Seeharnisch's power supply is as long duration as its air supply (weeks to months) it's still pretty slow.
Deep sea fish: well, fish is probably the wrong word. Eldritch horror? Well, getting conservation funding for fish is hard enough as it is without names like that, although if they're going to be named after you you can hardly be blamed for wanting them to go extinct as soon as possible.
The Seeharnisch is by no means as stealthy as it looks: oh, sure, it's quiet enough when it's walking along the bottom, but once those little propellers spin up for a pursuit, just one suit sounds like a very large swarm of particularly irate killer hornets. A pack of seven sounds like a legion of the damned.
To be honest here, the sort of damage they can do is pretty proportional to their noise; give some a few minutes to perform surgery on your pressure hull, and you'll have a set of breached compartments before you can say "what the hell's that grinding noise?"
Now, at the depths these things operate.. if you've got one holed compartment, it won't be five minutes before the unbearable pressures widen the hole until you've got three. You've got maybe two minutes from the commencement of the assault to hit the "Emergency Surface" button, and if you don't or you can't, that's it. You'll be having lunch with the crew of the Kursk fairly quickly.
If it's any consolation, the Kursk's crew died of starvation and suffocation, you'll be dying of having your ribcage smashed into your spine; at those depths, the jet of water from a hull breach is fast enough to take your arm off without you noticing it.
They can do the exact same things to command posts and research facilities: the general timeline is 2 weeks to walk along the seabed from a carrier sub to the target, then 30 minutes to cut sensor cables and airlock controls, 2 hours to saw through support legs and 3 more to carve open a convenient room. After that, the weight shift from the flooding station quickly shove it off its supports, and from then the end comes quickly.
Alternately, they have a secondary plan which is similar up to the airlock control disabling, but instead of disabling the airlocks they hack their way in and enter the base itself with their armours. The pressure plating on a suit like this is made to stand up to the crushing force of the deep ocean, a force that can crush a poorly designed suit of armour like an empty beer can before you can say "there's nobody in that, right?". The design process involved fast computers coming up with designs, testing them, and selecting only the toughest for further alteration. The result is probably the perfect design for the specific task. The hullcutters slung under the arms can carve through similarly tough pressure hulls on deep sea submersibles. The result of this is a suit of armour resistant to anything safe to use in an undersea facility, carrying powered blades capable of cutting through those same armours. The result of that is most definitely not pretty to look at. Needless to say, it tends to be traumatising for the pilots involved, but really, if you're going to volunteer to walk around for months on end on the bottom of the ocean, an environment that can kill you much faster than hard vacuum, you have to have something wrong with you.
So, a few notes about the design; the light on the shoulder is also fitted with a camera. The idea is that, if the suit exceeds its specified limitations, the man inside won't be crushed as easily as if the helmet was a weaker, viewport fitted design. The red patch on the back of the helmet is an identifying mark: it's illuminated when under the surface, to allow other members of the pack to see each other. The propeller assemblies are designed to fold into the 'backpack' when not in use, to keep them from getting in the way. Very handy. The pack itself contains a proprietary algae mix capable of converting carbon dioxide back into oxygen with far greater efficiency than normal air scrubbers, allowing a small supply of air to be used for a long, long time. It also does other things with bodily wastes, but I won't go into that. Also in there is a high density fuel cell, which is known for doing interesting things when charged too quickly. Interesting things which include catching fire (underwater, and refusing to be extinguished) exploding (violently and enthusiastically) attracting predators (magnetic effects. Nobody knows why it happens yet.) and inflicting fatal radiation burns on the occupant of the suit (which is part of a set of well documented phenomenons which also made small scale fusion reactors viable.)
More in the Kleinpanzer Week series:
Day One: AQ-6J Security Exoskeleton
Day Two: The Cambridge Device
Day Three: Exoskelettkleinpanzer Ausf-G
Day Four: Type VII battledress
Day Five: you're currently reading it.
Day Six: Flashman
Day Seven: Harpy
Day Eight: Fenrisulfr
Day Nine: DCA medical exoskeleton
Day Ten: Model IID Murderbot
Day Eleven: Space Marine armour
Day Twelve: MRB-L Scythe
Day Thirteen: CP-C riot armour
Day Fourteen: Black Guard armour
There's also a desktop background available, if anyone wants it: