Not just flora and fauna are getting caked in oil. So is the Gulf of Mexico's barnacled history of pirates, sea battles and World War II shipwrecks.
The Gulf is lined with wooden shipwrecks, American-Indian shell midden mounds, World War II casualties, pirate colonies, historic hotels and old fishing villages.
Researchers now fear this treasure seeker's dream is threatened by BP PLC's deepwater well blowout.
Within 30 km. of the well, there are several significant shipwrecks - ironically, discovered by oil companies' underwater robots working the depths - and oil is most likely beginning to cascade on them.
"People think of them as being lost, but with the deepsea diving innovations we have today, these shipwrecks are easily accessible," said Steven Anthony, president of the Maritime Archaeological and Historical Society.
"If this oil congeals on the bottom, it will be dangerous for scuba divers to go down there and explore," Anthony said. "The spill will stop investigations; it will put a chill, a halt on (underwater) operations."
The wrecks include two 19th Century wooden ships known as the Mica Wreck and the Mardi Gras Wreck. The German submarine U-166 and ships sunk by other German submarines during World War II are within the spill's footprint.