what are some methods of cleaning up big oil spills in oceans?

Answer 1

One method is to spray detergent on the oil to cause it to break up. Another method id to surround it with floating plastic booms and pump the oil (which floats on the surface of the sea) into an empty tanker. Some water will inevitably be pumped also, but this will separate out on standing.

Answer 2

the oil needs to be pumped out of the ocean. the nice thing about oil is that it floats. if it sinks, it's hard to clean up. you probably don't wanna add anything to the oil. the oil itself would cause damage to the ecosystem. chemicals could make it worse.