From Rodeo, paved RN 150 leads southwest to the foothill hot springs of Pismanta, where Hotel Termas de Pismanta (tel. 02647/49-7091, www.pismantaspa.com.ar , US$40 s, US$71 d, with breakfast, up to US$55 s, US$103 d, with full board) attracts mostly middle-aged and aging Argentines to its enormous hot baths and a decent restaurant that are both open to nonguests.
From Pismanta, RN 150 climbs 92 kilometers through the upper Jáchal drainage to the Chilean border at 4,779-meter Paso de Agua Negra, the highest pass between the two countries. Open at least December–March, it features an impressive glacier and the snowmelt pinnacles known as penitentes along the narrow highway, which continues to the scenic Elqui Valley and the beach resort of La Serena in Chile. San Juan  authorities envision keeping it open all year—highly unlikely without expensive tunneling.