For the first time since 2009 Lake Superior has frozen thick enough to safely permit access to the ice caves at the Apostle Islands National Lakeshore in northern Wisconsin. An estimated 1,000 people are arriving daily to trek out to the islands for a glimpse of frozen caves which are covered in a cascade of icicles formed from water runoff and waves that splashed against the caves before the surface solidified. If the weather holds out, officials estimate the caves could remain open for another month. A huge thanks to Kelly Marquardt, Andy Rathbun and the Wisconsin Department of National Resources for sharing photos of the caves. (thnx, Amy!)
Update: Journalist Andy Rathbun who provided many of the photos above, now has his own article about the ice caves over on the St. Paul Pioneer Press.