It undulates in dark, ominous smears on the face of the ocean. It glistens in thick, evil-smelling puddles the length of sandy beaches. It hangs in viscous, dripping tongues from shoreline rocks.
Fuel oil from the sunken tanker Prestige has blackened 400 miles of Spain's Atlantic seaboard and paralyzed some of the richest fisheries in Europe. And more is on its way.
With massive slicks still at large, the wreck of the Prestige leaking oil from 14 different holes, and the winds changing capriciously, "the more time passes, the more pessimistic I am," says Ricardo Beiras, professor of marine pollution at Vigo University, near some of the hardest-hit areas. "Given the length of the coastline affected and its commercial importance, this is going to be one of the worst oil spills in history."
More than 7,000 military personnel, state workers, and volunteers are scrubbing oil from the 200 beaches affected by the spill. Experts say it could take three years to empty the tanker, which is leaking at the rate of 125 tons a day, according to Mario Rajoy, Spain's deputy prime minister in charge of the government cleanup.
On Wednesday, winds from the west threatened to bring new oilslicks ashore, as recovery ships reported difficulty in pumping widely dispersed concentrations of oil that is thoroughly mixed with water after nearly a month in the open ocean.
"We think that the best way of proceeding, especially in areas close to the coast, is to use small boats," said Mr. Rajoy.
Fishermen in Spain's northwestern region of Galicia, welcomed the authorities' belated acknowledgement that they had been doing almost all the work themselves until this week, when the government sent in troops to help clean up.
"The politicians have not helped at all; it's out of their hands," says Jose Manuel Naveiro, a mussel fisherman in the port of O Grove who has thrown his boat into a desperate effort to keep the oil out of the inlets where thousands of families depend on collecting abundantshellfish for their living.
Strung out on the dock beside Mr. Naveiro was a makeshift barrier, ready for use to keep oilslicks at bay. Fishermen's wives, he said, had stuffed eiderdown filling into long tubes of sacking, then attached them to potato bags filled with polystyrene to keep them afloat.
Such primitive methods are typical of the struggle that the fishermen have been waging. From their tiny vessels they have been using garden rakes, fishing utensils resembling huge slotted spoons, and even their hands to scoop oil out of the water.
"We are winning the battle so far, but we haven't won the war" to keep the precious inlets clean, Naveiro says.
The enemy in that war has broken up into more than a dozen large slicks - some several miles wide - and many smaller ones dispersed over an enormous area off the coast of Spain, Portugal, and France. At the same time, the 60,000 tons of oil left in the tanks of the Prestige lies in two parts more than two miles below the surface, according to Rajoy, who said the government is studying ways of stanching that flow. If the full cargo of 20.6 million gallons of oil leaks, the accident will be the second-largest tanker spill in history. The spill will dwarf the 11 million-gallon Exxon Valdez disaster while falling short of the 78.5 million gallons lost by the Castillo de Bellver off South Africa in 1983.
The Dutch firm that initially tried to salvage the stricken tanker is reportedly readying a plan to pump oil from the wreck, but such an undertaking would be unprecedented at such a depth, and few experts believe it is feasible.
"Just with the oil already in the water, we could be at the mercy of the winds for several months," says Professor Beiras. "The oil in the ship is an even longer-term threat."
"We can't live with this sort of uncertainty for months at a time," complains Francisco Iglesias, head of the fishermen's cooperative in O Grove. "It would be like working with a knife at your throat."
Already the "black tide," as the disaster is known here, has been an economic catastrophe. Christmas is the high season for Galicia's much-prized shellfish, such as mussels, oysters, clams, and goose barnacles, and while the government has banned fishing in the region, the cooperatives themselves have banned shellfish collection so as to divert all boats to fighting the oilslicks.
"If the fisherman doesn't fish, his wife doesn't shop," says Maria Carmen Carrela, a store owner in O Grove. "We all depend on the sea here."
The gloom that has settled over the region is mixed with anger at the government, which fumbled for nearly a week about what to do while tugs pulled the Prestige first southwest, then north, then southeast. The authorities consistently played down the danger, and only last weekend sent soldiers and other government employees to join the cleanup.
Prime minister Jose Maria Aznar acknowledged this week that "we may have arrived late, or taken some wrong decisions," but insisted that no government could have been prepared to deal with what he called "this ecological piracy."
The delay in dealing with the spill contributed to the greatest difficulty that recovery boats now face - the dispersion of the slicks both on the surface and underwater. As the oil has weathered, mixing with seawater, its density has grown, meaning that it does not necessarily float. Fishermen have reported pulling oil-fouled nets from depths of 1,500 feet, and divers from the Rainbow Warrior, Greenpeace's flagship, found oil-coated lobsters off the shore of islands just north of Ons on Tuesday.
The oil that reaches the beaches can at least be cleaned up, though the process is painstakingly slow, as volunteers, soldiers, and others attack thousands of tons of thick, mousse-like glop with little more than their bare hands.
On Pereiro beach on the island of Ons, two miles offshore, a hundred or so park wardens donned white overalls, Wellington boots, face masks, goggles, and rubber gloves Tuesday, and got down on their hands and knees in the sand.
They were able to roll the puddles of congealed oil up into dough-like balls that they scooped with their hands into buckets lined with plastic bags. Then, working in pairs in a human chain, they heaved the buckets up steps cut into the bluff at the top of the beach, and emptied them into crates arranged along a track.
Watching them work from his home nearby, retired fisherman Cesario Perez shook his head and gestured at the rocks below, where his wife used to collect shellfish and hook octopus, now coated with a carpet of chocolate-colored oil.
"I can't tell you what is going through my head," he says. "This island is a paradise, and now we face mortal ruin."
At the end of their day's work, the wardens were filthy and exhausted, and they had collected about 20 tons of oil, clearing a patch of sand about 25 yards square. They left behind hundreds of tons on the surrounding rocks, and they knew that the overnight tide would bring in more.
"Tomorrow," sighed one of them, "it will be just the same as it was this morning."