[fffobar]

The Baltic Sea is very very shallow, with average depth of just 55 meters. It's not particularly difficult to do, sadly :(

"Fun" fact, mostly unrelated: the Baltic sea floor is full of unexploded munitions from WW2, and some (still?) contained chemical weapons.

[LargoLasskhyfv]

I'd think they would have cleared them before, instead of blindly laying some pipes in 'good faith'.

[fffobar]

Oh I'm sure it's cleared enough around the various pipes and cables that lie on the bottom. But it's still a far cry from the entire bottom of the sea being safe.