From Lago Viedma’s north shore, south of El Chaltén, the park’s best lake excursion is the Viedma Discovery’s full-day catamaran voyage to the Viedma glacier, which includes an ice-climbing component.

Sailing from Bahía Túnel, the vessel rounds the ironically named Cabo de Hornos (Cape Horn) to enter an iceberg-cluttered area before anchoring in a rocky cove. After disembarking, visitors hike to an overlook (the glacier is Argentina’s largest, though its lakeside face is small) with additional views of 2,677-meter Cerro Huemul. Those who want to can strap on crampons and continue onto the glacier for about 2.5 hours (even some sedentary city dwellers do so).

The bilingual guides know glaciology and provide more personalized service than the Fernández Campbell excursion from Puerto Bandera. While the price here does not include lunch, they do provide an aperitif on the glacial rocks.

Departure time from El Chaltén is 8:30 a.m., while the boat sails from Bahía Túnel at 9 a.m.; the cost is US$105 pp including transportation from El Chaltén. For details, contact Patagonia Aventura (Güemes s/n, tel. 02962/49-3110, El Chaltén, www.patagonia-aventura.com).