Beyond La Margarita, RN 40 climbs over the volcanic Meseta Escorial before dropping into the enigmatically named hamlet of Tres Lagos (Three Lakes; the only nearby water is the humble Río Shehuen). Northbound motorists must fill up at the YPF station, which has the only gasoline until Bajo Caracoles , 338 kilometers north.
Tres Lagos has few other services, though there is a pretty good municipal Camping Comunal (tel. 02962/49-5031, US$2.50 per tent plus US$1 per vehicle) with hot showers (US$0.50). Very good fresh-baked empanadas and other lesser snacks are available at the YPF station.
To the northwest, gravel RP 31 and RP 33 lead 100 kilometers to Lago San Martín, but unfortunately the landmark Estancia La Maipú, which used to offer accommodations, is presently closed.