Oil spill is mostly only a problem when tightly packed and form a continuous sheet on the surface. Emulsion is much less of a problem. North Atlantic witnessed plenty oil spills when the U-boat menace was active more than half a century ago. That never became a problem for the beaches or fishermen, except for when the "krauts" shot at them or landed. LOL.
Also, American subs sank 90+% of Japanese oil shipment in the waters surrounding the Philipines . . . that never became an environmental disaster.