It seems incredible, but in the 1800s, Norwegian sailing ships transported ice from Norway as far south as Africa. Just before the year 1900, Norway was the world's largest exporter of natural ice from lakes. It should be noted that most of the ice was not sent to Africa, but to England and the rest of Europe. Tons of Norwegian ice blocks were crushed and used for preserving fresh fish and other food items.
Much ice from freshwater sources in southern Norway, including places like Agder, was sold to private households and stored in iceboxes. These iceboxes were well insulated to ensure that the ice melted as slowly as possible. They were the refrigerators of their time.
Norwegian freshwater ice was also used for making ice cream before the advent of freezers. Crushed ice and salt were mixed in a ratio of 100 grams of ice to 23 grams of salt. This combination triggers a chemical reaction that requires more heat than is available in the two substances. The heat is taken from the surroundings, which consequently get significantly cooled down. In a cold mixture with the ratio of 100 grams of ice to 23 grams of salt, the temperature can drop as low as minus 21 degrees Celsius/minus 5.8 degrees Fahrenheit. When making ice cream, the mixture needed to be constantly stirred as it hardened into ice cream.
Ice was harvested when winter was at its coldest in January/February. The ice on Norwegian lakes and freshwater bodies could be over 1 meter thick. The ice was cut into blocks weighing about 250 kilograms. This was heavy and sometimes dangerous work, but it provided a much-needed income at a time of year when there was little other outdoor work available.