1.   Cleanup crews, meanwhile, skimmed oil off the water and lowered the boom.

2.   In past oil spills, cleanup crews generally have relied on skimming oil from water, still the preferred method.

3.   Skim the foam that rises to the top, being careful not to skim the oil.

4.   Four other ships were prepared to skim oil off the surface and three had chemicals to break down the oil.