As winds blow the oil southeast, away from land, on April 25, reflected sunlight turns the slick into an unfortunate silver lining (pictured in a NASA satellite image) for the clouds of crude now known to be gushing from the floor of the Gulf of Mexico.
At this point, the slick's "rainbow sheen" stretched about 40 by 30 miles (64 by 48 kilometers). The thick, dull layer of oil at the slick's southern edge (not visible), just above the seafloor leak site, measured roughly 16 miles (26 kilometers) long, according to a BP map.
The initial oil spill on April 22 had comprised about 8,400 gallons (31,800 liters) of oil, U.S. Coast Guard Petty Officer 3rd Class Tom Atkeson told National Geographic News on April 23, when the well was thought to have stopped leaking. That would have made it a "minor" spill, in the view of U.S. federal response agencies. (See "Oil-Spill Fears Subside at Rig-Explosion Site.")
But on April 25 the Coast Guard announced that remotely operated submersibles had found evidence that the pipe was leaking about 42,000 gallons (160,000 liters) of oil a day—a "very serious spill" and a threat to Gulf Coast ecology, Rear Adm. Mary Landry said at a press conference. (See "Oil Spill From Sunken Rig Site May Be Serious.")