Treasure Island, Florida -- Activists will gather on a beautiful beach at sunset Wednesday for a candlelight memorial and a call for action.
Holding candles to commemorate the workers killed when the Deepwater Horizon oil rig exploded, supporters say they'll stand on one of Treasure Island's public beaches and speak "with one voice."
Their call to state and federal officials: don't take your eyes off of the impacts of the Gulf oil spill -- and create serious rules to prevent a repeat of America's worst environmental disaster.
On April 20, 2011 -- one year since the spill began -- a light sheen of oil still sits on and just below the surface of a portion of the Gulf of Mexico.
Mud mixes with oil in a marsh near the mouth of the Mississippi River. It's part of what's left after more than 200 million gallons of oil spilled.
Eleven men died when a high-pressure blast of oil surged up from beneath the seafloor and into the Deepwater Horizon drilling platform, touching off a series of explosions.
"It's hard to know that's where my brother is -- he's at the bottom of the Gulf of Mexico," said Sarah Wiese, sister of 24-year old blast victim Adam Wiese, whose body was never found.
The explosion didn't just take lives. The oil spill it started wrecked the environment and rocked the economy in five states.
That includes areas like Tampa Bay, where only rumors and fear of oil arrived, but those forces were still enough to chase away customers in lifeblood industries like tourism and seafood.
A year later, Pensacola Beach restaurant owner Mike Prizone says business improving. "We've gotten a lot of locals and a lot of spring breakers. We're probably up 15 or 20 percent," he said.
BP is spending millions on promotional ads to bring back potential tourists.
"It's important that people know that our beaches are safe. They're clean and we just need people on them," said Tina Ross, who works for a chamber of commerce in a Mississippi community on the Gulf.
Tourists are coming back, but the debate continues over how much of the spilled oil remains, lurking in the Gulf.
The White House's top energy advisor has said 75 percent of the spilled oil is "gone" -- skimmed or burned from the surface, pumped into tankers from deep in the Gulf, broken down by natural processes, or widely dispersed.
But researchers from the University of Georgia adamantly disagree with that number. Instead, they figure 70-79 percent of the oil is still in the Gulf in one form or another.
Where is that oil? It's in the form of micro-droplets, including micro-droplets with a coating of chemical dispersant, that can be toxic to sea life, the scientists say.
Samples taken by St. Petersburg-based researchers have found super-small droplets of oil in some of the Gulf's most important areas for fish to breed and grow.
The oil is in DeSoto Canyon, about 60 miles south of Pensacola, according to scientists from the USF College of Marine Science in St. Pete.
They're concerned because the nearly invisible oil can kill off nearly invisible microorganisms that form the base of the food web for several larger species of sea life, including seafood that's the livelihood of many people around the Gulf.
"At least three-quarters of the oil is yet to be accounted for," said Chasidy Fisher Hobbs, staff scientist for the watchdog group Emerald Coastkeeper in Pensacola.
"Some is going to biodegrade and break down, but we don't know how much," she added. "Nobody has the answers... We're still dealing with oil on our beaches and in the water."
Researchers agree the full impact of the 2010 Gulf oil spill won't be understood for years to come.
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Grayson Kamm, 10 News