The GPS coordinates lead to a man-made structure with information about the local geography imprinted. The cache is hidden nearby.
A bronze plaque spells out the local legend, in Icelandic. Here's a rough English translation:
Oral legend has it that on the farm Saurbær in Siglufjörður, there lived a farmer called Álfur (i.e. "Elf"), who had gained much wealth as a viking early in his life. He was a pagan and well known for his magic, which always ensured him good catch of fish.When he was old, he had a huge burial mound dug for him, and had his ship placed inside it. As his death drew near he went inside the mound and took along with him all his treasure. He then had the mound sealed behind him, and placed a curse on it so that no one should be able to disturb the mound while his molars were still whole and had not turned to dust.Álfur's mound is now called Álfhóll (i.e. "Elf's Hill")
P.S. Please help keeping the disc clean by wiping off some of the seabird droppings. :-)