Alaska has an abundance of glaciers, although most of them are receding at a rapid rate due to increasingly warmer temperatures. The melt runoff from these glaciers forms streams and rivers that flow under the giant mass of ice above. As the temperatures increases during the summer months, the underlying rivers rise with a gray silty water that sculpts the surface ice above. In the winter, when the water ceases to flow, the water-hollowed caves can be accessed relatively easy. The arched, icy ceiling is sculpted in scalloped cups, sometimes radiant blue, and often decorated with frosty ice crystals. Although organic pieces of nature’s art, they can have unstable areas under your feet and overhanging rock above so they should be approached and entered with caution.