A single cask whisky is exactly that, one cask of whisky where the bottles filled only contain the whisky that has been matured in the same cask. Single cask barrels are very unique as wood is a living material, maturation may vary considerably from one cask to another making the whisky from every cask unique and unrepeatable. It's amazing to think that 2 casks made from the same tree, filled with the same batch of spirit, sitting beside each other in the same warehouse for the same period of ageing can taste completely different! That's what makes single cask whisky so unique and special.