The peated version of Islay led blended whisky, tempering the smokiness of the island malts with whisky from the mainland. 

Islay Mist was originally created on Islay in 1922 to celebrate the 21st birthday of Lord Margadale, the theory was that the intensity of the Islay malts might be too much for all the guests to handle.  So at the time some Speyside whisky and a grain whisky were blended with some Islay malts to create Islay Mist.