Fonte do Judeu Morto is a small settlement identified in the surroundings of Rio Seco, within the municipality of Castro Marim. The name is recorded in administrative documentation, including official publications related to municipal planning instruments such as the Municipal Master Plan. The traditional explanation for the toponym is preserved in local memory. According to a legend collected by the Centro de Estudos Ataíde Oliveira and recorded in the Lendarium, there once lived, “in ancient times”, a man known as “the Jew” who, while attempting to jump over a well, fell in and drowned, and it is from this event that the name “Fonte do Judeu Morto” is said to have originated.