Police are urging people to skate in safe environments, like the Ice Rink in City Square, rather than on treacherous frozen water in the city.
Currently the Brayford Pool is frozen, and so is River Witham.
DCI Shaun West said: “Young people are drawn to frozen over rivers and ponds as they think it would be exciting to skate or skid over them.
“The dangers are clear. The ice is never as strong as it looks and you only have to be in freezing water for a matter of minutes before your life is at risk.
“We want to do everything possible to avoid a tragedy like this happening.”