It looks like smoke. But the above photo shows the “‘smoke monster’ (for you Lost fans) effect of a massive midge emergence from the central (and probably also north) basin of the lake,” reports Claudio Gratton from the shores of Mývatn, a eutrophic lake in Iceland. “The wind was just right that they were corralled just for a time over the surface of the lake (that is not fog, or smog, but actually insects!),” he writes in his Smidge of Midge blog.