While these ice formations are nothing new, photos circulated on social media in 2014 introduced the caves to a new audience. The pictures garnered global attention, and more than 138,000 people flocked to the area. For the eight weeks that the ice caves were accessible by foot, this flood of people crowded into restaurants, booked hotels and drove up business at gas stations. Tourism to the Apostle Islands National Lakeshore in 2014 brought in an estimated $54 million in revenue for the area, including at least a $10 million boon tied to visitation to the ice caves, according to the National Park Service.