Traditional ISO tanks, used to transport bulk quantities of liquid, have recently faced some competition from what's known as a "flexitank." Essentially, a flexitank is a large plastic bag that goes inside a standard 20-foot dry box, similar to the design of a box of wine. After the liquid is transported, there is no clean-up required because the plastic bag is disposable. Though there are some challenges with the flexitanks, such as rupture/leak concerns on railroads, and their inability to transport hazardous liquid commodities (like spirits with high alcohol content), wine shippers have gravitated to flexitanks as their top choice for shipping wine to overseas markets. So that $300 bottle of wine you're drinking just might technically be "boxed wine." You can read more about flexitanks in this article from American Shipper: Boxed Wine.