Chile is best known for its red wines: cheap, plentiful and quite often excellent in quality and value. Cabernet sauvignon is most prevalent, though as I wrote last week, syrah, carignan and carmenere also can be quite good.

Chile’s white wines are underappreciated, which makes them potentially even greater values. There are no signature white grape varieties, such as the red carmenere or Argentina’s torrontes. The country’s whites are chardonnay, sauvignon blanc and, rare but often quite good, Riesling. The excitement is in exploring its various terroirs. Budget-conscious wine lovers eager to explore the influences of climate and geography on wine’s quality should focus here.

Wine recommendations: Chilean whites

Here’s why Chile is special, and this applies to whites and reds: The topography of the country, squeezed between the Pacific Ocean and the Andes Mountains, captures the beneficial influences of ocean air currents and mountain altitudes. The wine regions span the ideal latitudes of 30 to 50 degrees from the equator, including the traditional regions of Colchagua south of the capital, Santiago, to Aconcagua to its north. But in the past two decades, Chile’s winemakers have been exploring the edges of their geography.

“Twenty years ago, we had only a little over 60,000 hectares [150,000 acres] of vineyards specifically for wines, and now we have about 124,000 [300,000 acres],” says Marcelo Retamal, winemaker at De Martino vineyards, which produces wines in several wine regions throughout Chile. This national expansion has been accompanied by specialization, he said in an e-mail interview.

“If 30 years ago a particular location would have a variety of grapes including cabernet sauvignon, merlot, carmenere and chardonnay, nowadays we’re more selective and the vineyards are oriented toward producing grapes in their most favorable terroir.”

Those terroirs have been expanded to include Casablanca Valley, just northwest of Santiago, which opens to the ocean and specializes in chardonnay, sauvignon blanc and pinot noir. Farther north, the Limari and Elqui valleys push the extremes of desert climate with ocean and mountain influences. The Elqui, at the 30th parallel and the southern edge of Chile’s Atacama Desert, is the country’s northernmost wine region, closest to the equator. Winemaking there shows a frontier spirit. The wines are rough-and-tumble and benefit from intense sunshine. Look for grassy, aggressive sauvignon blanc and spicy, energetic syrah.

Farther south but still about 300 miles north of Santiago, the Limari Valley is poised to stake a claim as one of the world’s best regions for chardonnay. The valley sucks in the ocean fog to shroud and cool the grapes in the morning, gradually yielding to the mountain sunshine. Limari Valley chardonnay features great acidity and mineral quality, combining an Old World earthiness with New World fruit — literally the best of both worlds. Retamal’s De Martino Legado series 2010 Chardonnay is an excellent example of what this region can accomplish.

South of Santiago, winemakers continue to exploit the Andes and Pacific influences, but at cooler latitudes closer to the South Pole. Wines from these regions are still new to the U.S. market, so those from appellations such as Itata and Bio-Bio are hard to find. But if you come across them, try them.

Stretched north-south between the Pacific and the Andes, Chile offers a clinic in how geography affects the flavors and quality of wine. And we can explore this diversity without breaking our budgets. What more could we ask?

Wine recommendations: Chilean whites

McIntyre blogs at Follow him on Twitter: @dmwine.