The multi-talented Gerrit Korteweg was a competitive swimmer, artist, and architect. In the former Korteweg represented the Netherlands at the 1960 Roma Olympics, finishing eighth in the 4 × 100 metres medley relay and 20th in the 200 metres butterfly. Two years later he swam at the European Championships where he came fifth in the 4 x 200 metres freestyle relay. Away from the pool Korteweg studied architecture at the Technical University in Delft where he also had lessons in drawing and painting. In his later years his artwork focused on his time growing up in the Dutch East Indies during the outbreak of World War II.
Netherlands