Weather willing, the highly anticipated opening of the Apostle Islands ice caves is slated for Saturday morning, officials announced Wednesday. But beautiful icicles draped and dangling on sandstone cliffs won’t be the only attraction this year.

Those making the one-mile walk atop frozen Lake Superior will be facing an extremely treacherous but spectacular trek, officials warned. Visitors will have to tread carefully across clear, smooth ice best suited for ice cleats, allowing views to the lake bottom. In other areas, broken glasslike ice plates have piled up.

“The ice in many areas looks like window glass. … Even out near the cliffs, you can see boulders on the bottom of the lake,” said Neil Howk, assistant chief of interpretation for the Apostle Islands National Lakeshore. “It’s unbelievable. The way that the ice is frozen, in some places it looks like stained glass.”

As for the caves themselves, there is less ice hanging than last year, with the wind eroding some of the icicles, Howk said. But there are still some impressive formations, he added.

Park officials checked the ice conditions Wednesday afternoon after a windstorm blew through late Tuesday. It was the third time this winter that conditions looked promising, but winds broke up the ice the previous two times.

Howk said he’s not sure how long the caves could stay open this year, but warned it could be a short window, depending on the weather.

“I guess the message is, if you want to see them, don’t wait,” Howk said.

Last winter, an unprecedented 138,000 visitors flocked to the caves near Cornucopia, Wis. over the course of about 10 weeks. The caves were accessible for the first time in five years, and word of their beauty went viral on social media.

It was an onslaught and economic boon that surprised the communities in the area. The previous record for winter visitors to the caves was 12,000. The entire park drew 150,000 visitors in all of 2013.

Last season’s visitor deluge cost the park service far more than it took in from charging $3 per car in its small parking lot. Staff worked to answer phones and e-mails, direct traffic, plow snow and clean restrooms as well as rescue visitors who hurt themselves on the ice. Now the park will be charging a $5-per-person fee for ice cave visitors 16 and older. The money will be used solely to cover the costs, park officials said.

“This is a cost recovery fee. We only collect it if there’s actually an ice cave event and the money is directly used for that,” said Julie Van Stappen, chief of planning and resource management.

Ice conditions can still change quickly, park officials warn. There was at least 10-12 inches of ice all along the route Wednesday, but they are keeping an eye on some cracks, Howk said. In addition to ice cleats, officials recommend bringing ski poles for stability and leaving pets at home. They warn visitors to beware of ice formations falling from the cliffs.

Before making the trip, visitors should check for word of conditions at the park’s Facebook page, https://www.facebook.com/apostleislandsnationallakeshore, or by calling the Ice Line at (715) 779-3397, extension 3.