Sea dredger

Extracting resources hidden underwater is difficult and time-consuming. A sea dredger could extract resources such as sand or stone. Different modules could be created to extract different resources. Of course, this would be something separate to research in the research tree.

Definitelly good one, even having it just for sand would be great and also realistic (you can suck sand easilly - other resources would be harder to get this way).

Would give the shipyard and actuall further use as shipyard, build dredgers. But if we go that route, we should also build cargo ships instead of just buying them...