Sikker vs Ikke when ice skating in Copenhagen

The cold snap has turned the city's lakes, canals and even harbour into outdoor skating rinks. However not all are safe and sometimes the signage is confusing, especially for us non-danish speakers. "Sikker" is safe and "ikke" means not - important distinction!!  

In addition to signage, the Copenhagen Kommune (council) publishes updates on whether lakes are safe for ice skating on their website.  It says in part:

When the temperature for a few days has been below freezing, we measure the ice thickness on the city's lakes. If the ice is sufficiently thick, approx. 16-18 cm, it is possible to open for traffic. We would stress however that the thickness is only suitable for general use as ice skating and walking, and that dangerous situations can occur if many people crowd together in a small area and, for example jumping or dancing.

We're looking forward to trying it out (though no crowding together or dancing!!).