For the first time in five years, visitors to Lake Superior’s Wisconsin shore can experience the winter beauty of the Apostle Sea Caves—completely frozen and safe to visit, thanks in large part to the Northern Hemisphere’s exceedingly low temperatures this winter.

National Park Service officials, who monitor conditions along the Apostle Islands National Lakeshore, say that the last time Lake Superior’s ice was thick enough to safely hold visitors to the caves was back in 2009; but with weeks of frigid temperatures caused by the polar vortex, Lake Superior has iced over enough to support adventurers on their one-mile trek from mainland Wisconsin out to the caves.

Check it out in this video from CNN: