They symbolized the annual cycle of death and rebirth in nature, and presumably fasting and ritual purification in the sea took place before the large procession.  
Celebrated well into the Christian era, the lesser of these festivals was held in the early spring at Agrae.  They symbolized the annual cycle of death and rebirth in nature, and presumably fasting and ritual purification in the sea took place before the large procession.  FTP, name these rites that celebrated the changing seasons through the myth of Persephone and Demeter, held in a small town near Athens.
Celebrated well into the Christian era, the lesser of these festivals was held in the early spring at Agrae.  
Eleusinian Mysteries