RENEE MONTAGNE, HOST:
And there are a lot of words we're using to describe this winter of the polar vortex: brutal, unrelenting - that's a couple - but how about stunning? The deep freeze has brought great beauty to a group of islands way up north floating in Lake Superior.
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DAVID GREENE, HOST:
They're called the Sea Caves of the Apostle Island. They're right off the shore of Wisconsin. And in the summertime, kayakers paddle in and out of these sea caves.
MONTAGNE: In a winter that is cold enough, one can strap on snowshoes and trek over the frozen lake to visit the caves. Imagine this: a stiff wind and bone-deep cold. You walk and walk and then enter a glittering world of ice.
BOB KRUMENAKER: This is almost like a pipe organ, cathedral, where there's just row after row of icicles of every size and shape. And in this area, they're all the same color. They're all clear.
GREENE: That is Bob Krumenaker, the superintendent of the Apostle Islands National Lakeshore. The caves are filled with the ice version of you might see in other caves, what looks like stalactites, waterfalls, waves, outcroppings made of glass. Sometimes the ice is crystalline or milky white or it has a reddish tint from contact with the sand and rock.
KRUMENAKER: Here, we've got very delicate descending ice formation. It looks like it slid over the top and then very slowly melted on the way down. So, there's these very vertical striations.
MONTAGNE: He's looking at icicles 10, 20, 30 feet long - the length of a cliff descending toward the lake. And if you make the trip, you won't be alone.
GREENE: It is the first time in years that the caves have been accessible over the ice. In just 10 days last month, more than 10,000 people visited. Jim Talkinton(ph) drove seven hours all the way from Rockford, Illinois.
JIM TALKINTON: We were just talking about how it was just the worth the drive up here just to see this. It's pretty cool.
MONTAGNE: Another visitor said looking up in the caves was like looking into a grand chandelier made of frosted glass.
GREENE: I'm just picturing all of this. It really is making the bitter cold a little less bitter.
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GREENE: This is NPR News.