Somewhere on this part of the road you cross from the valley of San Martin into the lake district proper, and the first of the lakes appears among dark forest. The seven lakes along the route are glacial, scooped out by ice during the last ice age and filled with meltwater, and each has its own colour, from steel blue to green to a milky turquoise when the light is right. Machonico, Falkner and Villarino are among those you pass, and they line up like beads along the road.
Fill the tank before leaving San Martin and bring something to eat, because there are only a few small kiosks and campsites in the forest. Those places open in summer, and their hours are unpredictable.
The riding is among the best in Argentine Patagonia. The road weaves through the forest in long, smooth bends, sometimes climbing, sometimes dipping to a lakeshore. Most of it is paved and in good condition now, though a few gravel sections remained until recently, and it makes sense to check the current state. Look out for cattle and for sudden patches of damp under the trees. In the early morning, mist hangs over the water and the forest smells of moist earth and cinnamon-scented bark.
This is also protected land, and much of the road passes through Lanin and Nahuel Huapi national parks. The forest holds southern beech, the strange monkey puzzle tree on some slopes, and cypress, and in the lakes there are trout, brought in by early settlers and now a big draw for fly fishermen. Condors circle above the higher ridges, and you may see a fox cross the road at dusk. Stop at the signed viewpoints to take photographs, since the road itself has few places to pull over safely. A thin jacket will not do here; the temperature can fall quickly.