Several years ago people started making small cairns in the area below the information sign for Þingvellir National Park. The cairns proliferated for a while, were knocked down my the authorities and erected again by passers-by, and now seem to have gained acceptance. They make nice foreground detail for photographing the lake.
When I took the photo below there were two other people there. The man was adding rocks to various cairns and the woman was photographing him and both were assuming all sorts of strange poses while doing it. The woman assumed several of the funny poses you see photographers use when they are concentrating deeply on their subject, including the crouch, the half-split and the limbo, and I think I saw the man, out of the corner of my eye, rise up from something resembling the downward dog yoga position. I only regret not having photographed them, but I think maybe they might have gotten mad if I had disturbed the strange ritual they appeared to be engrossed in.
Anyway, here is photo of the cairn garden: