Two Iowa men pleaded guilty Wednesday to marijuana charges in Canada after they fell through the ice of a partially frozen river while trying to illegally enter the country from Michigan's Upper Peninsula.

Daniel Rathjen, 19, of Marengo and John Lindley, 19, of Iowa City each pleaded guilty to a charge of possession of marijuana for the purpose of trafficking, said Constable Al Montgomery of the Royal Canadian Mounted Police.

Another charge they faced, possession of marijuana for the purpose of export, was withdrawn.

The case began when the men bought about 1 1/2 pounds of marijuana, worth about $2,800, in Toronto, Montgomery said.

The men thought they could avoid border control by crossing a narrow strip of the St. Mary's River, running between Canada and the United States, Montgomery said. But they found the river wasn't fully frozen when they arrived in Sault Ste. Marie, Ontario. So on Jan. 10 they stuffed four plastic bags filled with marijuana into a duffel bag, which they then hid under a private covered dock along the river.

Rathjen and Lindley told police they drove more than 500 miles back to Iowa, then after a week noticed the Iowa River had started to freeze. They assumed that if the Iowa River was frozen, then the St. Mary's River would also be frozen, Montgomery said.

They drove to Michigan's Upper Peninsula and took a ferry to Sugar Island. From there, they attempted to cross the quarter-mile to the Canada shoreline on Jan. 20. Just 26 feet from the border, they fell through the ice.

Residents called 911, but the two managed to make it to the Canada side.

"A neighbor ... gave them a hot drink and change of clothes because they were freezing," Montgomery said.

The men told authorities they came to retrieve the stashed marijuana, and officials found the drugs at the dock, buried under a pile of snow.

Both were sentenced to serve 75 days at an Ontario jail.