Did you know Lake Superior has ice caves?

For the first time in half a decade, the ice atop Lake Superior has frozen thick enough to provide visitors safe passage to the "Sea Caves" of Wisconsin's Apostle Islands, where centuries of erosive, wave-on-sandstone action have hewn arches, chambers and passageways into the region's various cliffsides.

Photo Credit: National Park Service, via the U.S. Department of the Interior's Instagram (which, if you're not following, you really should be)

Via the U.S. Department of the Interior:

Inside the caves awaits a fairyland of needlelike icicles. The formations change from chamber to chamber and from day to day. Apostle Islands is experiencing high volume of visitors right now, so we recommend that you visit the caves during the week. Before heading to the caves, please call the Ice Line at (715) 779-3397 - extension 3, for the most current ice condition information.