Participants also ward off evil during the festival by bathing in flower-scented water, wearing five-colour silk, hanging plants such as moxa and calamus over their doors, and pasting paper cut-outs in their windows.

UNESCO: Culture

Upriver here and at the Sandrift River, which runs parallel 10 miles to the east, the colour of the water is striking - imagine looking into a cup of strong, dark coffee.

BBC: The perfect trip: South Africa

This substance (an iron-magnesium silicate whose greenish colour is reminiscent of olives) weathers rapidly in the presence of water.

ECONOMIST: Martian chronicles