A week ago I met the Danube again, for the fourth time on my journey – flowing between Romania and Serbia, dividing Middle Europe from the Balkans.

Here, in the the riverside town of Orșova, is the point where Between the Woods and the Water ends. Since Paddy sailed from here, however, on a steamer bound for Vidin, Bulgaria, the town and the landscape around it have undergone apocalyptic change. Between 1972 and 1984, the communist governments of Romania and Yugoslavia constructed two vast hydroelectric dams across the legendary Iron Gates, turning one of the river’s wildest and remotest stretches into an enormous reservoir. The valley was flooded for hundreds of miles, displacing many thousands of people from villages along both banks, completely submerging Orșova’s old centre and wiping the island of Ada Kaleh – an ancient Turkish enclave oddly left behind when the Ottomans withdrew – out of…