The Kontxako Bandera (Basque) or Bandera de la Concha (in Spanish, meaning "Flag of the Kontxa") is one of the oldest and most famous estropada race along the Bay of Biscay, held annually in the Kontxa, the main bay of San Sebastián, Spain. It takes place on the first two weekends in September and regularly draws crowds of more than 100,000 people and around 20 rowing teams. It was first held in 1879 and has been held most years since with the main exception of the war years.
In Galician it's called Bandeira da Cuncha and Drapeau de La Concha in French.