Different bodies of waters always have some sections where ice is weaker. These sections are:
- Fast flowing parts of a river, as constantly moving layers of water hinder the growth of ice;
- Estuaries or places where, for example, two rivers meet, or where a river runs into a lake or sea. In such places, whirlpools and eddies prevent ice formation;
- Wetlands, and areas near piers and fallen trees. Ice does not quickly form in these areas and oxygen exchange is taking place through the “holes” surrounding the objects;
- Springs – water bodies with springs always freeze more slowly, because the spring water temperature is constantly above 0º C;
- Water outlets – places where a sewage pipe, for example, enters a body of water. Water coming from the pipe is warmer and thus slows down the ice formation process;
- The vicinity of shipping lanes – the ice in the vicinity of shipping lanes is regularly broken to keep the lanes clear of hazardous ice.