Caol Ila 25 Year Old is a continuation of two cask-strength limited releases from 2004 and 2005, though it's bottled at a significantly lower 86 proof. This run was released in 2010, and seems to be mostly unavailable via retail outlets as of 2016. It is, however, available through a number of auction houses and resellers at a significant markup.
Caol Ila Distillery was founded in 1846, and takes its name from the Gaelic term for the Sound of Islay, the strait between the islands of Islay and Jura that it overlooks. It is one of the most critically-acclaimed distilleries on Islay, but is less well-known in many areas than its legendary neighbors Lagavulin, Laphroaig, and even Ardbeg. Caol Ila is pronounced "kuh-LEE-luh," for those not up on their Scots Gaelic.