Here at the border of Surses and Bergell, a raindrop has the choice of heading for one of three seas. If it goes north, it travels along the Rhine until its journey ends in the North Sea. If chance takes the raindrop eastwards, it goes into the River Inn in the Engadin and then via the Danube into the Black Sea. Or it may go to the south-west, from Lake Como into the River Po and then the Adriatic (Mediterranean). One drop, three choices – the water divide at Lunghin is a curiosity, the only one of its kind in Europe.