Checking out the next section of my hike, behind me and to my right, I could see that the ridge of the Muttenbergen curled like the top of a question mark, arcing from the Muttenstock to a peak called the Ruchi to another called the Rüchi. Tucked in the curve of the question mark was a snowy basin called the Mutten, filled for the most part by an icy lake called the Muttsee. I could see the trail as a line of bootprints running across the snow covering the rib that held the Muttsee in place, and there on the rib stood a little square dot, black in the piebald mix of snow and rock. My map identified this building as the Muttseehutte, SAC (Swiss Alpine Club). When I got there it would be caffe fertig time for sure.

Under my feet the space over the Limmerensee looked like an enormous roofless room, long and narrow, with the lake as its blue carpet. The wall on the other side of the lake was a horizontally banded cliff, rising sheer from the water to my own height; above that it broke up and lay back in a wild jumble of snow and boulders, ending in a jagged skyline that ran from peak to peak-from the Vorder Selbsanft to the Selbsanft to the Hinter Selbsanft to the Vord Schiben to the Hinter Schiben. All these names made sense in relation to my vantage point, as if they had been named from there.

The Muttsee and the Limmerensee were both blue, but the blues were very different. The Muttsee was the brilliant turquoise of water lying over submerged ice, under a clear sky. The Limmerensee, on the other hand, was a reservoir, and its catchment basin included two hanging glaciers that added glacial milk to the clearer waters coming in from elsewhere. The resulting mix was the opaque virulent blue of radiator antifreeze.

The reservoir flooded a valley which must have been quite something before it was drowned. The mapmakers had retained the contour lines of the submerged area, turning them blue rather than the usual brown, and these showed what had probably been meadow or forest, or a mix of the two, with the Limmerenbach running down the middle.