Ice caves could be ready for visitors in the coming week, according to officials at Apostle Islands National Lakeshore. This shot was from last year/NPS.

Close, but not quite ready. That's the situation at Apostle Islands National Lakeshore in Wisconsin, where the frigid temperatures of late are making progress on freezing over Lake Superior and creating the "ice caves" on the lakeshore's mainland cliffs.

"Getting close," lakeshore Superintendent Bob Krummenaker said. "Definitely will be closed this weekend, but a week from now, it's looking pretty good."

The caves -- featuring a fanciful array of icicles, ice sheets, and frozen draperies that form in, on, and around the caves Lake Superior eroded into cliffs -- appeared last winter and attracted an estimated 138,000 people to wander through them. That unprecedented visitation received national and international attention. The unexpected tourism -- the caves hadn't formed since 2009 -- generated nearly $10 million in revenue to the local communities.

But it also cost the National Park Service roughly $450,000 over the 10-week period the caves were accessible. To avoid another financial squeeze, the lakeshore proposed, and gained approval, for a $5 per person fee for those 16 and older. An annual pass of $10 per person is available for those who want to view the ice caves more than once during the winter months. The $5 fee will be collected onsite at the Meyers Road parking area near Bayfield, Wisconsin. The annual permit, however, must be purchased at park headquarters in Bayfield.

The anticipation that the caves will be iced over soon has brought more than a few phone calls to the lakeshore, and prompted lakeshore officials to post this on their webpage:

Ice has been forming on Lake Superior, however, the ice has NOT met the established criteria yet to consider the caves accessible. Rangers are completing daily visual checks to determine ice shelf spread. Once the ice is locked into geographic mainland points, Rangers will hike out (with cold water immersion suits on) and drill holes in the ice to measure thickness and evaluate conditions. It is only after favorable conditions are documented that the NPS considers the ice caves accessible. Hold on! We're getting closer!

Officials add that ice condition information can be heard by calling the Ice Line at (715) 779-3397 - extension 3. This is a basic "yes" or "no" response. Staff will change the message ASAP if ice conditions allow access to the caves. They also plan to update their Facebook page regularly.

The ice conditions can be fickle. Twice this winter the lake has frozen over near the ice caves, and twice the ice has blown away, the lakeshore staff reports.

This is how things looked Wednesday/NPS