The focus of the heatwave has since moved further east, with temperatures in Austria hitting successive national records this week, peaking at 41.2C on Wednesday. Such a warning indicates a potential health emergency with prolonged high temperatures posing a serious health ​risk to the entire population. Low water levels are causing problems ​for shipping on the Rhine in Germany, where many vessels can sail ‌only part-loaded, raising freight costs. The river is an important shipping route for commodities such as grains, minerals, coal and oil products. In Bosnia, tourists have taken shelter in the constantly cool temperatures of the UNESCO-listed Vjetrenica cave to escape outside temperatures of 40C.