A four-hour drive takes us to the River Spey. Speyside marks the heart of Scotland's whisky country. It's practically a pilgrimage for aficionados of Scotch whisky.

Of the hundred or so whisky distilleries in Scotland, about half lie near the valley of the River Spey. Its prized waters, along with a favorable climate and soil for barley, have attracted distillers here for centuries.

Along with natural resources, a critical element in the Scotch-making process is quality barrels. The Speyside Cooperage welcomes visitors with guided tours. From an observation deck, you'll watch master coopers making casks for distilleries throughout Scotland. Perhaps the single biggest factor in defining whisky's unique flavor is the barrel it's aged in.

The process is essentially the same today as it was centuries ago. In order to be watertight, the oak staves are lassoed tightly by metal hoops. Tight-fitting lids are banged into place and sealed with a calking of fresh-water reeds. Finally, the inside is artfully charred, creating a carbonized coating that helps give whisky its golden hue and flavor.

The United States actually contributes to the character of Scotch whisky because most of the barrels used in Scotland are made from the staves of hand-me-down bourbon casks from Kentucky. It's impressive to watch the coopers — who are paid by the piece — work with such intensity and focus.

The distilleries that put Speyside on the map for whisky-lovers are bigger and more corporate than others in Scotland, and they include some famous names — including one of the world's best-selling brands, Glenfiddich.

The sprawling Glenfiddich Distillery offers tours that show the basic steps in making Scotland's beloved spirit.

They've been turning barley into whisky here since 1886. After the grain has been germinated, or "malted," it's put in these tanks called "mash tuns." Water — distinctive to each region — is added to this mash to extract the sugars.

The resulting liquid, or "wort," is transferred to tanks called "washbacks." Yeast is added to ferment the sugars into alcohol. The liquid at this stage is called the "wash."

The wash is then heated in copper stills where it's concentrated, or "distilled," into spirits. The shape of the stills and the combination of various strengths of the spirits are unique to each distillery. It's like moonshine gone corporate.

The spirit is then put into wooden casks, where it matures for a minimum of three years before it can be called "whisky" in Scotland.