http://www.allscandinavia.com/surstromming.htm
...Caught in the months of May and June, processors immerse the fish (herring) for a day in brine and then decapitate and clean it. Next they stack it in barrels, trundling it out into the summer sun and left there for 24 hours to get the fermenting process started. An inch or two of space is left at the top of each barrel so that any gas formed during the fermentation can accumulate with out causing an explosion...
Among those who like surstromming best....there's the belief that the contents of a can left for a year at a temperature of 68̊ F. actually improve; the can will have begun to swell, and at its puffiest must be opened gingerly, like a bottle of champagne...
Sales of surstromming are on the increase in Sweden, but its future as an export item is, predictably, dim.... the product doesn’t always travel well. Only recently a Swede found this out. Thinking to amaze an important New York client and the assembled board of directors with so bizarre a food, he produced the swollen can he had carried all the way from Sweden in his luggage and dramatically laid it on the table. At that moment, the can exploded.
I bet that left an impression. LOL