In the midst of their 1,800-mile hike around Lake Superior, Mike Link and Kate Crowley are facing, of all things, a deadline.

They have to be in Sault Ste. Marie on Saturday to cross the Sault Ste. Marie International Bridge from Michigan into Canada; it's the only day of the year that the bridge is open to pedestrians. Bad weather and bad knees have hindered their ideal progress of 15 miles a day. "But we did 19.3 miles [June 13] and still had some energy left at the end," Link said, via e-mail.

Link, 64, and Crowley, 60, are two months into their five-month hike, documenting the shoreline's ecology while promoting fitness for all ages. Link said his knees "have given me a lot of trouble," but he met a surgeon along the way who had some suggestions. Crowley needed a cyst on her back removed, which caused another brief delay.

As to the lake, they've been disheartened -- and taken aback -- by the balloons washing up on shore. "Both latex and Mylar," Link said. "Every day they show up. Found one yesterday -- Happy Mother's Day, with air still in it."

Across Michigan's Upper Peninsula, lakeshore development seems almost continuous, with cabins "more like mansions than summer homes." Yet he added that some stretches remain too rugged to walk "and we are pleased to know of the wildness of the tip of the Keweenaw [Peninsula]."

Many lakeshore residents have anticipated their arrival, although the couple suspect that may change as they move into Canada and beyond the range of much of the news coverage that's preceded them. To follow their progress, visit www.fullcircle superior.org.