The Tristaina Lakes are three glacial lakes stacked on a rock staircase at 2,300 metres in the north of Andorra, and they are not three pools of one stream. The ice dug a basin wherever the granite under it was weakest and rode straight over the harder rock between, so when it melted each hollow filled separately and the three ended up at three different heights. A stream now spills from one into the next. Estany Primer comes first, the smallest and the bluest, ringed with grass and a few wind-bent pines leaning over the water, and the loop crosses the outflow more than once, which is what makes the three read as one staircase rather than three ponds. Marmots whistle from the boulder fields on the way up. They are newcomers: the species died out in the Pyrenees around 15,000 years ago, and the animals here descend from marmots brought over from the Alps last century.
You do not see all three together until the end. The path keeps climbing past the top lake to the crest of the circuit, and only from up there do the basins stack into a line behind you, with the French Pyrenees on the other side. Within days of the snow letting go, alpenrose — the low rhododendron of these mountains — flowers across the slopes below the water. From late September the grass and bilberry heath turn copper and rust, and the lakes look almost black against them. Winter takes them away altogether: under snow the basins are level ground and the rock steps between them are the only shape left, so nothing shows where the deep water lies. On the crest stands a steel ring 25 metres across with a 27-metre mast leaning through the middle of it. The mast is not a flourish. It is tilted to the latitude and aimed at the pole star, the hours are read around the ring, and the thing you are standing on to count the lakes is also telling you the time.