Bone-chilling images from the arctic blast

The arctic blast that sent temperatures in the Midwest and other parts of the country plummeting has provided some spectacular, bone-chilling imagery.

In Wisconsin, subzero temperatures have allowed outdoor enthusiasts to view Lake Superior's hidden caves for the first time in five years. The Apostle Island sea caves, about a mile offshore, are accessible by walking across the iced-over lake.

Instagram users uploaded photos of the rarely seen ice caves on Sunday, when temperatures reached a high of 7 degrees. On Monday, high winds combined with minus-14-degree conditions made it feel like minus 38 — a dangerously cold day for ice cave-viewing.

In Iowa, near-whiteout, blizzard-like conditions were captured on camera by Jones County resident Theresa Golden Bacon during Sunday's winter storm. Temperatures in Jones County were 30 degrees on Sunday with wind gusts as high as 58 mph; on Monday morning, it was minus 8 degrees with wind chills of minus 34.

In Idaho, the extreme cold recently led to a rare sighting of an ice disk, an unusual natural phenomenon that occurs in slow-moving water. This one, captured on video by Daniel Ostler last week, shows an ice disk on the Snare River.