To create The Balvenie Port Wood 21 Years, a marriage of rare Balvenie is transferred to seasoned oak casks, which have previously held vintages of fine Port wines. These barrels of maturing Malt are regularly sampled by The Balvenie Malt Master to ensure that just the right amount of Port Wood character is imparted by the casks, enhancing and developing the Single Malt whilst preserving its distinctive qualities and character.