These tanks hold fermenting wines in our outside cellar. The grapes go from the selection table into one of these, and if it's a red, it generally goes into cold-soak for a couple days before warming to inoculate with yeast. The cold-soak process involves maintaining a low temperature by keeping dry ice in the tank 24 hours a day. It also keeps the fruit covered in a layer of CO2 which preserves its quality to extract color from the skins.
Cold inside the tank, but pretty pleasant working outside with the sun shining.