A giant tanker refitted to scoop up spilled oil is being tested at the site of the Gulf of Mexico oil leak.
The Taiwanese vessel - called "A Whale" - is designed to vacuum up oily water, separate the oil and return the water to the sea.
It is undergoing two days of testing before starting work, a Coast Guard spokeswoman said.
Much smaller skimming vessels have been working off Louisiana, but they have been affected by rough seas.
Oil has been gushing from a ruptured well in the Gulf of Mexico since 22 April, when BP's Deepwater Horizon rig exploded and sank.
Crude oil has been leaking at a rate of between 35,000 to 60,000 barrels per day, according to US scientists.
Two containment ships capturing about 25,000 barrels of oil per day are now in place, and there are plans to double this by connecting a new vessel, the Helix Producer.
But these plans have been delayed by tropical storm Alex, which brought high seas and strong winds to the region.Clean-up boost
Testing of the giant skimmer vessel - which its owners say can process 21 million gallons of oily water per day - began on Saturday.
The 275m (300-yard) tanker takes in oily water through 12 vents.
In a series of tanks, the oil is separated for transfer to another vessel, while the clean water is returned to the sea.
THIS SHIP CAN TAKE IN DAILY THE SAME AMOUNT THAT ALL OTHER SKIMMER SHIPS HAVE COLLECTED TO DATE.
SO WHY IN THE HELL DID OBAMA DELAY ITS ARRIVAL!?
CLOWARD-PIVEN I GUESS: OBAMA AND HIS COMRADES GAMBLED THAT THE BIGGER THE CRIS9IS THE MORE THE ELECTORATE WOULD HATE "BIG OIL" AND SUPPORT "THE GREEN ECONOMY".
I THINK THEY GUESSED WRONG. THE ELECTORATE BLAMES OBAMA FOR THE INEPT RESPONSE. EVEN JAMES CARVILLE DOES.
I PRAY THEY STAY AWAKE THROUGH NOVEMBER AND VOTE GOP@!