Is the Baltic pretty miserable looking below surface?
It's not tropical waters, it's colder, the visibility is lower, etc.:
bestdivers.pl/dlaczego-my-o-bestdivers/publikacje-w-mediach/artykul-ku-przestrodze/
wrakibaltyku.pl/pl/c/o-nurkowaniach-w-baltyku.html
"
About diving in the BalticDiving in the Baltic is special. It's hard to compare it to other waters in the world. The green colour of the water, the often changing visibility and weather conditions require special training, knowledge and diving skills from the diver.
The magnet that draws divers to this region of the world are the numerous shipwrecks, some of them, because of their uniqueness, are counted among the top spots for diving in Europe."
I imagine for a military frogman it was a walk in the park.
It's really a puddle, not a sea.
Then why don't you try it and see for yourself... Oh wait, but you can't enter Poland... can you? :) 😁