Scientists say oil from BP's damaged well in the Gulf of Mexico is clearing from the sea surface faster than expected, 100 days after the disaster began.
The National Oceanic & Atmospheric Administration says much oil has been biodegraded by naturally occurring bacteria.
It says oil has come ashore along nearly 1000km of the Gulf coast shoreline.
But the agency also says the amount on the surface of the sea is less and less as aggressive efforts to contain it have been successful.
US Coast Guard Admiral Thad Allen says oil skimming crews are having trouble finding oil to clean up.
The leak began on 20 April after an explosion and fire on the Deepwater Explorer drilling rig. It was finally stopped on 15 July.