This may not look much but, to hydrologists, its heaven. It's a watershed, deep in the Rupununi Savannah (Guyana). From here, the water runs off to join the tributaries of Essequibo in one direction, and the Amazon in the other. During the wet season, these two mighty river basins are linked by floodwaters, and the eastern Guianas become – if not exactly an island – completely encircled by water.
The first person to recognise this phenomenon was the great explorer and hydrographer, Alexander von Humboldt in 1800. He also recognised that, in the absence of any other lakes of maritime size, the flood plain had to be the fabled ‘Lake Parima’ from the myth of El Dorado.
From Tudor times onwards, many lost their lives in the search for this lake, and the golden city. In reality, there is nothing here but golden grass. A few still believe that there might be something out there - but not many.
Evelyn Waugh, writing in 1933, was typically sniffy about the non-existent lake. Even Charles Waterton, the great naturalist, becomes uncharacteristically snappish when he gets here, and finds nothing but the dust. ‘So much for Lake Parima,’ he writes, ‘and so much for El Dorado.’