Dangers Posed by Floating Mattresses on Lake Constance for Mariners and Swimmers - Lake Constance water pants: Potential hazard for vessels and swimmers
Lake Constance, a large inland lake in Central Europe, experienced a rare weather event on Tuesday when a water spout reached approximately 800 meters into the sky. This phenomenon, visually similar to small tornadoes, is characterized by a rotating column of air and water vapor.
Water spouts are more common over Lake Constance than in other regions of Central Europe, with an average of 2 to 3 recorded by the German Weather Service each year. They form under atmospheric instability and warm water surfaces, such as the recent warming trends that have raised Lake Constance's temperature above 24°C in summer 2025.
For swimmers, waterspouts pose a significant risk due to strong winds and turbulent water motion. They can create dangerous currents and suction effects that may pull swimmers underwater or cause injury. For small boats, waterspouts are hazardous because their strong wind speeds and sudden formation can capsize boats, toss them violently, or cause collisions with debris.
Despite the risks, the Lake Constance Shipping Company reported that only experienced ship captains are on the lake, and the catamaran service was not affected by the weather event on Tuesday. Large ships, in general, are not in danger from water spouts, but ship captains try to avoid them.
The water spout over Lake Constance was a Type 2 tornado, according to the German Weather Service (DWD). Type 2 tornadoes do not require a thunderstorm to form and move relatively slowly over the water or hardly at all. The average wind speed of a water spout is around 100 kilometers per hour, with some reaching speeds similar to weak tornadoes.
Swimmers and boaters should avoid waterspouts by seeking shelter indoors or onshore if spotted and monitoring weather forecasts for unstable conditions in the region. It is essential to stay informed and take necessary precautions to ensure safety during such weather events.
Sources:
- Waterspouts: An Overview
- Lake Constance Warming Trends
- The environmental aspects of Lake Constance, with its warming trends and weather events such as water spouts, necessitate observance of the community policy regarding swimming and boating activities to ensure safety, particularly in light of the findings in environmental science and the characterization of water spouts by the German Weather Service and the DWD.
- Being aware of the higher frequency of water spouts on Lake Constance than other Central European regions and understanding the role of atmospheric instability and warm water surfaces in their formation, as evidenced by the environmental-science research, can help swimmers, boaters, and ship captains take appropriate measures to mitigate risks and maintain safety during these events.
