Lakes, fjords and other waterways in Denmark should be considered off-limits for walking or skating unless signs clearly mark that it is safe to do so. That is not the case in many places, despite the current sub-zero weather.

In Copenhagen, 18 people were charged last weekend after breaching rules to walk on frozen lakes, police said.

“I hope what was communicated today has helped so that residents in Copenhagen have had their eyes opened to that fact (walking on frozen lakes) can be dangerous,” Paw Kaltoft of Copenhagen Police told news wire Ritzau.

“I don’t know of anyone in Copenhagen who has fallen through the ice. But it has happened in other places,” he said on Saturday evening.

That includes three people who fell through ice on the island of Mors in North Jutland, and an incident on Zealand which required a helicopter rescue, the news agency reports.

News broadcaster TV2 reported that police had charged individuals with trespassing on the ice.

According to Danish law, individual municipalities decide when ice is thick enough for the public to be allowed to walk on it.

Although rules can therefore vary locally, the ice must generally be at least 13 centimetres thick. In Aarhus, the ice layer must be 16 centimetres, according to Ritzau.

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