Some 220km southwest of Mendoza, LAGUNA DIAMANTE is the destination of one of the least-known but most unforgettable excursions in the area. The source of the Río Diamante, the lake is so called because the choppy surface of its crystalline waters suggests a rough diamond. One reason for its relative obscurity is that weather conditions make it possible to reach Laguna Diamante only from mid-December to the end of March. At Pareditas, 125km south of Mendoza by the RN-40, take the reliable, unsealed RP-101, which forks off to the southwest; the drive is one marvellous panoramic view of the Andean precordillera, following Arroyo Yaucha through fields of gorse-like jarilla and gnarled chañares, affording views of the rounded summits of the frontal cordillera, before entering the Cañón del Gateado, through which the Arroyo Rosario flows past dangling willows. At another fork in the road, 20km on, take the right fork to the Refugio Militar General Alvarado, the entrance to the Reserva Provincial Laguna Diamante. Here, you’ll catch your first sight of Cerro Maipo (5323m), the permanently snowcapped volcano that straddles the frontier, some 4000m above sea level. Nestling beneath the Cordón del Eje, a majestic range of dark ochre rock, and towered over by the snow-streaked Maipo opposite – a perfect cone worthy of a Japanese woodcut – this ultramarine lake is constantly buffeted into white horses by strong breezes and its waves noisily lap the springy, mossy banks. The silence is broken only by the howl of the wind.