With the well capped and the spill breaking up, it's now tough to find any oil on the surface of the Gulf. On Tuesday, skimmers collected only 155 barrels of oil and water. By contrast, on July 8, they picked up 25,000 barrels.
CBS News Correspondent Mark Strassmann noticed a changed, visibly cleaner Gulf while flying over Mississippi's entire coastline Wednesday with the Civil Air Patrol.
More on Spill's 100th Day
Even small patches of oil were rare.
"It looks tremendous," Capt. Randy Stastny said.
Stastny flew over the coastline Wednesday for the first time in three weeks.
"I really expected the shores to be covered; not at all," said Stastny. "Huge change. I'm really tickled pink."
From early May on, BP's shifting oil blob ballooned. By late June, it spread from Louisiana to Florida's panhandle.
BP capped the well July 15. Nearly two weeks later, the Gulf is dramatically different with a much-shrunken, scattered spill.
Scientists credit the skimming and burning efforts as well as Mother Nature with bacteria in warm water degrading the light crude.
"It's a horrible event," said Louisiana State University's Ed Overton. "It's like a car accident. You break bones but normally you heal from all of the breakage."
On Day 100, the disappearing surface spill is the good news.
The lingering worry is what can't be seen and what BP seldom talks about: vast underwater oil plumes and their unknown impact on the ecosystem.
One worry? So-called undersea dead zones where oil starves oxygen from the water and its marine life of fish, shrimp, oysters and crabs.
"There's going to be an impact like that that's going to be felt for a long time," Overton said.
In Orange Beach, Ala., Robert Stuart's worried about a different dead zone, his 220 rental cottages. Seventy percent of them are empty with no sign of recovery.
"Once the leak was capped, it was the beginning of the end," said Stuart. "In fact, I think it's the end of the beginning."
A new report captures that anxiety with ten times the usual Gulf coast beach closings this summer. Most had no oil at all. The challenge now is convincing tourists the coast really is clear.