On April 25th, the patron saint of San Marcos is a very special day. On this day, it is a custom in Hondarribia for the godmothers to offer their godchildren (if still single) an Opila (sponge cake) containing as many eggs as the godchild has. The day begins at mid-morning when the children, young and old come to the churches, with the Opilak wrapped in a napkin for their blessing.
Later in the day, people climb up the nearby mountains and spend the day in the fields of Guadalupe.