Superman had his Fortress of Solitude, a cave he carved out of ice to have a place to weigh his ontological angst. Since he could fly, access was never an issue. Not so in Wisconsin, where tens of thousands of people have taken advantage of this year's deep freeze to hike across Lake Superior and visit the dramatic ice caves accessible by foot for the first time in years.
The caves are at the western end of the Mainland Unit of Apostle Islands National Lakeshore in far northern Bayfield County. They were carved out of sandstone by the waves from Lake Superior, the largest by volume and surface area of the five Great Lakes. The lake system, linked by a man-made seaway, has about one-fifth of the entire planet's surface fresh water and this year is more than three-quarters frozen.
In warm times, the caves are reachable by boat, but when the temperature falls to the point where frigid seems like a heat wave, Lake Superior freezes. This winter's icy grip has made the ice thick and stable enough to allow people to walk across and marvel at the crystalline wonder of stalactites and stalagmites. It has been five years since the caves were so reachable.
More than 35,000 people have hiked the more than one-mile route across the ice in the Apostle Islands shore since officials declared the ice a "low risk" on Jan. 15, park spokeswoman Julie Van Stappen told reporters over the weekend.
"We have never had this number of people coming," she said. "It has been a bit overwhelming, but it has been great for the local community, and [the caves] are gorgeous."
Van Stappen said the round-trip trek to the caves can take three hours or more over a well-packed and slippery path with little cover to break the sometimes fierce winds.
"Travel on Lake Superior can be dangerous any time of the year," officials warn on the park's website. "Traveling across the ice demands extra attention to personal safety. Because of the unpredictability of lake ice, traveling across it is never completely safe. Before heading out, visitors must understand all of the risks involved, and the physical demands required for hiking out to the caves."
Still, the number of visitors has been surging over the three-day Presidents Day weekend.
Quick, how many presidents came from Wisconsin?
(Spoiler hint: the current governor, Scott Walker, who has made noises about running for the GOP nomination, would be the first president from the Badger State, if he runs and wins the Oval Office.)
Freaky weather also brings freaky phenomena in its wake. Excessive cold has been blamed for everything from cracked lips to cracked pipes.
At least one other phenomenon has also been reported: cryoseism, or frost quakes – a favorite of terrified social media users. When temperatures drop, underground water can freeze and expand, cracking nearby rocks and soil. The sounds are like deep gunshots or explosions, but rarely do disasters result.
Mother Nature is not always fun and games. Nasty winter surprises are possible from other causes, as well, but fortunately they too are rare.
A spate of volcanic activity in 1815, including the mega-eruption of Mount Tambora in what is now Indonesia, helped bring about the so-called Year Without Summer in 1816, when severe food shortages took place in the Northern Hemisphere. Crops couldn't grow properly in the cold caused by lack of sunshine getting through the haze, according to one theory.
Even the majestic beauty of Wisconsin's ice caves come with a warning:
"The ice formations at the sea caves are beautiful, but they are very large chunks of heavy ice," officials caution. "They can fall at any time, so try not to spend much time underneath them."