It took torches, massive mittens and dives into frigid waters, but the Soo Locks in Sault Ste. Marie, Mich., opened Tuesday on time.

The opening of the locks marks the start of the Great Lakes shipping season.

Crews battled the elements to put the Poe Lock back into operation as scheduled, the U.S. Army Corps of Engineers said Tuesday. Maintenance on the MacArthur Lock beside it will continue for several weeks.

The locks closed for the winter on Jan. 15 and "underwent critical repairs and maintenance during the winter shutdown," a Corps news release says.

Because of harsh weather and ice, this year's repairs were "tougher," spokeswoman Lynn Rose said by phone.

Lock and dam operators had to use torches to melt ice that formed on latches, according to the Corps' Facebook page. "Temperatures well below freezing made ice a constant challenge."