Ore patches now spill over into the sea as submerged variants. Dredge them up with new floating hardware, and build deeper into the blue with water-placeable refined concrete.
I have Dredgeworks and Ocean Dumping. This might be a fun interaction between them. Ocean dumping allows me to treat oceans like lava, voiding things. Land drills will stop because the spot is full. Floating drills dump into the ocean, which might normally stop them (I'm not sure, I just added DW.) but they're just going because of OD.
