Actually, it could be. It's probably a mass of dead plankton which died off because of rising sea temperatures.
Around 10-15 years ago, the same thing happened off the Icelandic Westfjords, which is the north-west part of Iceland. At first, it was believed to be a spill of the waste matter from fish oil production, but then scientists determined it was caused by a mass death of some species of plankton, which are really small, almost microscopic crustaceans or similar. This particular species was quite oily and died off en masse because of increased sea temperatures or some such.
As I said, I can't remember any useful details, but that's more or less what happened back then, sometime near the end of last century off the coast of North-West Iceland.