There are a lot of unexploded mines and other ordnance around in the Baltic, I think it's actually very common to use these sorts of drones for minesweeping.
Fun fact: The best naval ordonance disposal teams are from the Baltic states. The difuse more live ordonance, from WW1 and WW2 in a week than the US counter parts see in training, non-live ordonance in a year (might also be in a month, they diffuse a ton so. Similar to all the civil ordonance disposal companies we have in Germany, albeith the Baltic divers work under much more dangerous conditions).
https://en.m.wikipedia.org/wiki/Seafox_drone