It’s way too large to operate safely and clandestinely in the Baltic Sea. It’s a crap shoot if it could even transit the Denmark Strait submerged without getting run over or grounded.
My opinions….
Max draft in the straits is 45 feet. That beast draws 30 feet on the surface. No way it could even submerge. And if it tried to sneak through, like you said... it get plowed over.
And then having that WWII Battleship sized behemoth trying to do clandestine work in 200 feet of water? LOL... sure.