Florida Keys residents may not have seen massive tar balls and fish kills after the 2010 Deepwater Horizon oil spill, but small concentrations of toxic crude were still reaching the islands and potentially harming marine life, as the extent of the deadly disaster in the Gulf of Mexico was worse than originally thought, according to a University of Miami study. Nearly a decade after the worst offshore oil spill in U.S. history killed 11 people and dumped 200 million gallons of crude into the ocean, researchers found discrepancies in the satellite footprint that was used to establish fisheries closures and data from sampling and field tests. They concluded that the real extent of the BP oil spill may have been 30 percent larger than originally estimated. After methane seeped into the rig and triggered an explosion on April 20, 2010, oil gushed from a pipe more than 4,000 feet below the ocean’s surface for 87 days. Read more at our news partner, the Miami Herald .