Strangely beautiful, until you realize just how ghastly the stuff is....
![](http://s.ngeo.com/wpf/media-live/photos/000/196/cache/gulf-oil-rig-spill-colors-show-depth_19688_600x450.jpg)
Gulf Oil Colors
Photograph by Chris Graythen, Getty Images
Both the size and color of the oil slick on the water's surface are indicators of how much oil has actually flowed into the Gulf of Mexico so far, said Doug Helton, incident operations coordinator for NOAA.
A silver-grey sheen or rainbow color, as seen in the above picture taken Wednesday, indicates a thin sheet of oil—perhaps only a molecule wide, he said. Authorities have said that the majority of oil seen on the surface of the Gulf—well over 90 percent—is spread out into such a thin layer. (See a picture of the silvery oil spill taken by a NASA satellite.)
But dark black patches indicate that thick pools of oil lie beneath—as much as five barrels-worth of oil per acre (0.4 hectare) in the darkest areas. The extent of dark patches seen in the Gulf led NOAA observers to believe that previous flow estimates were too conservative, Helton said. The size of the spill now covers several thousand square miles.
![](http://s.ngeo.com/wpf/media-live/photos/000/196/cache/gulf-oil-rig-spill-rise-surface_19690_600x450.jpg)
![](http://s.ngeo.com/wpf/media-live/photos/000/196/cache/gulf-oil-rig-spill-river-of-oil_19691_600x450.jpg)
![](http://s.ngeo.com/wpf/media-live/photos/000/196/cache/gulf-oil-rig-spill-nearing-coast-satellite_19689_600x450.jpg)
more
http://news.nationalgeographic.com/news/2010/04/photogalleries/100429-gulf-oil-rig-spill-worse-pictures/