In the winter, waterfalls at Pictured Rocks National Lakeshore in Michigan freeze into amazing formations of natural art. Water seeping out of the porous sandstone cliffs can also freeze into curtains and columns of blue, white or yellow ice. The ice generally begins to form by mid-December and can remain until early April. Some skilled climbers travel to the park to ascend these formations using ice axes and crampons. It’s really something to see. Photo by National Park Service.