Ice, Ice, Baby

At over 29km (18 miles) long and 5km (3 miles) wide, Perito Moreno glacier is often described as one of the greatest natural wonders of the world. Glistening castles of ice tower 45m (150 ft.) over the surface of Lake Argentino, where ice calves the size of apartment buildings go crashing into the lake every few hours. The entire glacier is an enormous shifting mass of creaking, groaning ice that can move and crack without notice; hikers are strongly advised to seek out an experienced guide before trekking across this beautiful but dangerous icescape.

The town of El Calafate (a 3-hr. flight from Buenos Aires) is most visitors’ first stop before taking the 2-hour bus journey into Los Glaciares National Park (www.losglaciares.com), a 607,028-hectare (1.5 million-acre) wonderland of mountains, forests, glaciers, and lakes that was declared a UNESCO World Heritage Site in 1981. Tours of the glacier can take up to five hours on a full tour, which often includes a surprise break of chocolates and whiskey chilled by—what else?—fresh-chipped glacial ice. There’s also a shorter “mini-trek” that takes roughly 90 minutes. Hikers on either tour can expect to wear crampons, or metal spikes that attach to their hiking boots, when traversing the ice. There are also boat tours that glide across Lake Argentino, giving visitors close-up views of calving icebergs and the lofty clifflike face of the glacier.

Every few years, the glacier advances far enough to form a natural dam across part of the lake; as a result, one side of the lake rises up to 30m (100 ft.) above the other. When this happens, pressure builds up in the higher part of the lake until the ice barrier explodes in a spectacular eruption. It’s impossible to predict when this will occur, but those lucky enough to witness it are treated to an event they’ll never forget. Los Glaciares National Park is also home to several other impressive glaciers, including Upsala and Spegazzini glaciers; adventurous hikers may also want to take in Mount Fitz Roy and Cerro Torre, a massive spike of granite that’s among the world’s most challenging climbs. —ML

Tours: Interlagos ( 02902/491179; interlagos@cotecal.com.ar). SurTurismo ( 02902/491266; www.surturismo.com.ar).

When to Go: Nov–Apr.

El Calafate (48km/30 miles).

$$$$ Los Notros, Parque Nacional Los Glaciares ( 11/4814-3934; www.losnotros.com). $$ Miyazato Inn, Egidio Feruglio 150, El Calafate ( 02902/491953; miyazatoinn@cotecal.com.ar).