Between 2011 and 2013 a group of outdoor swimmers swam the 250 kilometer length of the non-tidal River Thames in stretches, starting at the source and ending in Teddington on the outskirts of London. The numbers varied from stretch to stretch, and the project took on a life of its own. Stanley Ulijaszek discusses this art-work-like swimming project with four of the founders of Swim the Thames.