Extremely cold weather in the US Midwest has allowed thousands of people to cross one of the deepest parts of the Great Lakes on foot, giving them the chance to see unique ice caves for the first time since 2009. The unseasonably cold weather along the lake's shore creates a gallery of ice formations, and the minerals from the porous sandstone cliffs create a rare display of color. Al Jazeera's Kimberly Halkett reports from the Apostle Islands National Lakeshore in Wisconsin.