By the fourth dram, my glow had become a bit warmer and a light fog was settling in. A good single-malt Scotch can do that to you. The Highland Park distillery, on the far northern Scottish island of Orkney, was our third whiskey tour and tasting in three days.

In late September, my wife wanted to see rural Scotland, her ancestral home - and I wanted to drink in the land's rich bounty. Scottish single malts are on fire - sales have almost quadrupled in the last decade, by catering to style-seeking millennials and those tired of colorless, soulless spirits with names like Goose and Tito.

"We may not get them [drinkers] till they are 25 or 30, but once we do, they don't leave us," says Nick Morgan, head of whiskey outreach for Diageo LLC, owner of many single-malt brands.

Conveniently, many of Scotland's great distillers are tucked away deep in the countryside - amid the bright-green mountains of the Highlands or the beautifully forbidding waters of the North Sea and Atlantic Ocean.

"Distilling in Scotland began as a form of agriculture, so many of the great ones are in rural, farm areas," says Robert Cassell, founder and master distiller of Philadelphia's New Liberty Distillery. Cassell studied distilling in Scotland before opening his operation in Philadelphia.

Single-malt distilling seems blissfully simple: There are just three ingredients - barley, water, and yeast. Peat fuels the fires that roast the barley used in many whiskies. Broadly, flavors can be divided into two categories, peated (smoky) and unpeated (you guessed it, non-smoky). Aging in oak casks significantly affects the flavor - as well as the price. Many 25-year-old whiskeys can reach $1,000 per bottle, clearly not the stuff you'd wash down with a can of Schmidt's.

There are 118 distilleries and five whiskey-producing regions in Scotland. We had neither the time nor livers to see them all. We set out for three regions, trying to hit one or two in each.

Islay

There are few better regions to experience rural Scotland and the distilling process than the island of Islay on the west coast. An hour by plane from the capital of Edinburgh, Islay has a spare, austere beauty. Just 25 miles from Ireland, it is buffeted by the North Atlantic. Legend has it that Scottish distilling began there, brought by Irish monks in the 14th century.

You can experience four seasons in a day there, bone-crushing wind and a driving rain can instantly give way to bright sun, illuminating some of the prettiest landscapes in the country.

There are few trees and no stoplights. Charming, whitewashed houses line the streets, adjacent to warehouses filled with barrels of maturing whiskey. The island is home to 3,000 people, 30,000 sheep, and eight distilleries - including Laphroaig, Lagavulin, and Bowmore.

"Most Islay whiskeys are peated. That's the most distinct character," said Georgette Crawford, the energetic distillery manager at Lagavulin. "They also give a taste of the place, so there are notes of salt, medicinal seaweed, and wood-burning that build together for a distilled taste of Islay."

Tours at most distilleries average about $9. That gets you a lesson in distilling and at least one dram of Scotch, though more money or a bit of charm can get you a few more drams.

Bruichladdich, which stands out as the only distiller on the island that offers gin, was shut down in the '90s but reopened several years later. It launched Botanist gin in 2011, partly because it needed a product to sell while some of its Scotch still needed a few years to age. Gin, however, can be turned around in a day. Producing gin might have seemed like heresy to purists on "whiskey Island," but Botanist remains a staple of Bruichladdich.

Highlands

The Highlands are Scotland's Big Sky country and, geographically, it's the largest whiskey-producing region. Majestic mountain ranges dominate much of the land, and the northern Highlands face the North Sea. Sparsely populated, it is great for hiking, fishing, hunting, golf - and, of course, distilleries - 39 in all, including Highland Park, Talisker, and Glenmorangie.

"Traveling the Highlands is an adventure in itself, but whiskey lovers turn it into a sensory adventure story too, using distilleries as the anchor point with which to plot their tasting journey," says Hamish Torrie, global brands ambassador for Glenmorangie.

As we drive toward the Glenmorangie Distillery along the North Sea, our vista is interrupted by idle oil derricks - testament to the world's oil glut.

The whiskey business is in stark contrast. Glenmorangie hums along, producing about seven whiskeys of different age and temperament.

A great reason to visit this distillery is spending a night at the adjoining Glenmorangie House. Glenmorangie is Gaelic for "glen of tranquillity." And it sure fits. The 17th-century farmhouse, converted to a hotel, is a stone's throw from the water, with terrific food and roaring fireplaces. It doesn't get much better than sitting by that fire, single malt in hand, then walking to the water and looking up at the brightest stars and moon you will ever see. Rooms are about $350 a night but worth it.

If you have the time, I would recommend a trip to the island of Orkney to see the Highland Park distillery. If Orkney is not the windiest place in the world, it's close - that wind produces a dramatic, treeless landscape and good Scotch. Peat has more heather there, rendering a sweeter taste to the spirit.

Speyside

Speyside is a must stop on any whiskey tour. About half of all distilleries in Scotland are there, including the best-known names: Macallan, Glenlivet, Glen Grant. It's the northeast corner of the Scottish Highlands and includes the lush, fertile valley of the River Spey.

The abundance and quality of the water and the presence of barley fields were the principal reason distillers flocked to Speyside in the 18th and 19th centuries, but there's more to that story. Before distilling became legal, Speyside was considered an ideal spot for illegal stills - it not only had the ingredients but was far enough away from Customs in London not to cause a stir.

Most distillers there use little or no peat, instead malting the barley with hot air, giving Speyside a taste of its own.

"Speyside whiskeys are different in as much as they tend to be more fruity than other areas of Scotland," said Dennis Malcolm, master distiller at Glen Grant.

The Glen Grant distillery tour takes advantage of the bucolic Spey environs. A stream runs through the property, with Adirondack-style fences and a bridge. Reminds one of northern Bucks County.

The river gave birth to the whiskey business there, but it's also considered one of the world's great salmon-fishing spots and was the setting for the film Salmon Fishing in the Yemen.

Our own movie ended after seven days and seven distilleries. We learned more about peat, barley, and malting than we will ever need to know. But we experienced something more important.

"It [Scotch whiskey] is their heritage, their national pride; it's great to see it all," says Cassell.

Slange ("cheers") to that.