In Senegal, on the western coast of Africa, one of the most ancient and manually ways of producing sea salt is still practised. The base source for the regional salt workers is the Saloum river in southern Senegal which flows into the Senegalese Atlantic coast. Its delta is rich in mangrove forests and is part of the Saloum Delta National Park and Unesco Biosphere Reserve world heritage site.

Because the water in the Saloum river flows so slowly, the delta allows saltwater to travel deep inland. The farmers understood the advantage of the salty water and developed a way to harvest sea salt. With very primitive tools, they dig hundreds of small ponds into the shores of the river bed. Narrow canals connect the ponds with the river. Seasonal high tides flood the shallow ponds with seawater.

Solar evaporation turns the water into a salty brine. Due to variable algal concentrations, vivid colours, from pale green to bright orange, are created. The colour indicates the salinity of the ponds. Microorganisms in the water change their hues as the salinity of the pond increases. In the summer months, the brine turns dense enough to crystallize, and the salt crystals fall to the bottom of the pond, where they can be scooped out.

This intense labour work is done by entire families that live in surrounding villages. During the harvest season, every morning before sunrise, they walk several kilometres from their huts through the arid land to their salt ponds. If lucky, accompanied by donkeys that carry a basic, wooden trailer where the salt will be loaded. Extraction occurs in conditions of blazing sun and extremely high temperatures. Young children, mainly girls, carry up to 25 kg sacs of salt on their heads for as far as 15 kilometres to the nearest pick-up point.

The saltworks on the shores of the Saloum river Delta resembles a remarkable testimony of the synergy between a natural environment and a style of human development that is still carried out in such primitive practices. Seen from above, the salt ponds appear as multicoloured cells and rectangles of an earthy colour palette. Thin lines cross the landscape mark the tracks of the salt workers reaching their ponds. These abstract, man-made structures are a visual school for the untrained sight. Our eyes need to engage with the pattern, and our brain must decipher it to understand what we see.