Mar 3, 2014

In northwestern Wisconsin, crowds of people flocked last month to trek on a frozen-over Lake Superior to reach dramatic ice caves accessible on foot for the first time in several years, courtesy of the long frigid winter. The ice caves on Superior’s shoreline are carved out of sandstone by waves from the lake and derive their name from the icy freeze in winter that makes them glisten with hoar frost, icicles and ice formations. Reachable in warm weather by boat, the caves are accessible in winter only by walking across ice when it is thick and stable enough. Text and photos by Reuters

: A woman photographs ice formations at sunset on a rock face of the Apostle Islands National Lakeshore of Lake Superior, the world’s largest freshwater lake, to the sea caves near Cornucopia, Wis., on February 14, 2014. According to the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory, about 94% of Lake Superior is covered with ice, enabling thousands of people to visit the islands on foot for the first time since 2009. The Great Lakes, which contain one fifth of the world’s surface fresh water, are 88% covered with ice. (REUTERS/Eric Miller)

: Matthias Doherty slides down an ice wall in a sea cave of the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Sightseers look at ice formations in sea caves of the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Sightseers look at icicles at the mouth of a sea cave of the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Pete Miller, from Minong, Wis., looks through an opening with his dog at the sea caves of the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis. (REUTERS/Eric Miller)

: Sightseers are framed by the icicles of a sea cave as they trek across a frozen expanse of Lake Superior, the world’s largest freshwater lake, at the Apostle Islands National Lakeshore near Cornucopia, Wis. (REUTERS/Eric Miller)

: Sightseers crouch to avoid icicles in a sea cave on frozen Lake Superior, the world’s largest freshwater lake, at the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Icicles and hoar frost form on the ceiling of an ice cave by Lake Superior, the world’s largest freshwater lake, at the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: A man rests on frozen Lake Superior, the world’s largest freshwater lake, at the sea caves of the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 15, 2014. (REUTERS/Eric Miller)

: The propeller of a ship is frozen in Lake Superior at port in Superior, Wis., on February 15, 2014. (REUTERS/Eric Miller)

: Sightseers trek across a frozen expanse of Lake Superior, the world’s largest freshwater lake, to the sea caves of the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Sightseers look at a frozen rock face along the Apostle Islands National Lakeshore of Lake Superior, the world’s largest freshwater lake, near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Sightseers trek across a frozen expanse of Lake Superior, the world’s largest freshwater lake, to the sea caves of the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 15, 2014. (REUTERS/Eric Miller)

: Jeff Neddo, from Eagle River, Wis., tightens new crampons on his boots at the sea caves of the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: A woman walks her dog at sunset on a frozen expanse of Lake Superior, the world’s largest freshwater lake, by the sea caves of the Apostle Islands National Lakeshore near Cornucopia, Wis., on February 14, 2014. (REUTERS/Eric Miller)

: Mike Rundle, from Janesville, Wis., looks at ice formations in a sea cave at the Apostle Islands National Lakeshore of Lake Superior near Cornucopia, Wis., on February 15, 2014. (REUTERS/Eric Miller)