Deepwater Horizon victims' families
mark first anniversary of oil spill
On land, vigils were scheduled in Louisiana, Mississippi, Alabama and Florida to mark the moment on the night of 20 April last year when the rig, owned by Transocean Ltd, burst into flames while drilling a well for BP.
The explosion killed 11 workers on or near the drilling floor and the rest of the crew were evacuated before, two days later, the rig sank to the seabed. The bodies of the dead were never recovered.
Over the next 85 days, 206m gallons (5m barrels) of oil – almost 20 times more than was spilled in the 1989 Exxon Valdez disaster – leaked from the well. In response, the US commandeered a fleet of vessels in an effort to contain the spill, and BP spent billions of dollars to cap the well and clean up.
"I can't believe tomorrow has been one year, because it seems like everything just happened," Courtney Kemp, whose husband Roy Wyatt Kemp was killed on the rig, wrote on her Facebook page on Tuesday. "I have learned a lot of things through all of this but the most important is to live each day as if it were your last … what matters is if you truly live."
In a statement, President Barack Obama paid tribute to those killed in the blast and thanked the thousands of workers and volunteers who "worked tirelessly to mitigate the worst impacts" of the spill.
"But we also keep a watchful eye on the continuing and important work required to ensure that the Gulf coast recovers stronger than before," Obama said in the statement.
Transocean invited up to three members of each family to attend the flyover. They were expected to circle the site a few times in a helicopter, though there is no visible marker identifying where their loved ones perished. On the seabed 11 stars were imprinted on the cap of the well.
While ceremonies mark the disaster, oil is still occasionally washed up on beaches in the form of tar balls, and fishermen face an uncertain future.
Louis and Audrey Neal of Pass Christian, Mississippi, who make their living from crabbing, said it had got so bad since the spill that they face foreclosure as the bills keep piling up.
"I don't see any daylight at the end of this tunnel. I don't see any hope at all. We thought we'd see hope after a year, but there's nothing," Audrey Neal said, adding that financial difficulties were only part of the problem. "Our lives are forever changed," she said. "Our marriage, our children, it's all gotten 100% worse."
She said the couple received a $53,000 (£32,000) payment from BP early in the crisis, but that was just enough money to cover three months of debt. They have as yet received nothing from the $20bn compensation fund set up by BP, they said.
The outlook is, however, not all bleak. Traffic jams on the narrow coastal roads of Alabama, crowded seafood restaurants in Florida and families taking their holidays along the Louisiana coast attest to the fact that familiar routines are returning, albeit slowly.
"We used to fuss about that," said Ike Williams, referring to the heavy traffic heading towards Gulf Shores, Alabama, where he rents chairs and umbrellas to beachgoers. "But it was such a welcome sight."
"It seems like it is all gone," said Tyler Priest, an oil historian at the University of Houston. "People have turned their attention elsewhere. But it will play out like Exxon Valdez did. There will be 20 years of litigation."
Most scientists agree the effects "were not as severe as many had predicted", said Christopher D'Elia, dean at the school of the coast and environment at Louisiana State University. "People had said this was an ecological Armageddon, and that did not come to pass."
Biologists, however, are concerned about the spill's long-term effect on marine life.
"There are these cascading effects," D'Elia said. "It could be accumulation of toxins in the foodchain, or changes in the food web. Some species might dominate."
Accumulated oil is believed to lie on the Gulf seabed, and it still shows up as a thick black crust along miles of Louisiana's marshy shoreline. Scientists have begun to notice that the land in many places is eroding.
Confidence in Louisiana's seafood is eroding, too. "Where I'm fishing it all looks pretty much the same," said Glen Swift, a 62-year-old fisherman in Buras who works the lower Mississippi river again. But he cannot sell his fish. "The market's no good," he said.
But the BP spill has faded from the headlines, overtaken by the tsunami and nuclear disaster in Japan, unrest in the Middle East and political clashes in Washington.
"Nationally, BP seems like a dim and distant memory," said Douglas Brinkley, a Rice University historian. But the accident will have long-lasting influence on environmental history, he said.