As geo-political wheezes go, it is ingenious. Architects in Chile think the way to meet neighbouring Bolivia’s century-old demand for restored access to the sea is to dig a 150km tunnel running under Chile’s border with Peru, ending up at a man-made island in the Pacific.

Sovereignty would be punctiliously respected on all sides, and the Bolivian armada, left literally high and dry by a bloody 19th-century conflict that lost the country its maritime provinces, can break out from the tributaries of the Amazon and the heights of Lake Titicaca, reconverting from brown-water fleet to blue-water navy. Bingo.