On July 17, the Orthodox Church honors Saint Marina (Margaret). This day celebrates individuals named Marina, Marin, Marinella, Margaret, and their derivatives. Saint Marina, who lived in the 3rd century in the ancient city of Antioch, now part of present-day Turkey, desired to embrace Christianity through Holy Baptism. Unfortunately, no priest was available to perform the sacrament, and Marina was subsequently tortured and sentenced to death for her faith. Despite brutal torture, she remained steadfast in her faith, and several miracles, including her legendary escape from a demon in the form of a dragon, are attributed to her.

For Bulgarians, Saint Marina is a symbol of heavenly fire, overseeing harvest and sowing. She is also believed to possess a healing gift, which is why many medical facilities in the country are named after her. The day is known as "Marinden" in the national calendar and marks the last of the three hottest days of the year. Saint Marina is regarded as the guardian of the waters and protector of the Southern Black Sea.

In Sozopol, the feast day of Saint Marina, the great martyr, is celebrated as the city's festival. The new Sliven Metropolitan Arseniy will lead a solemn Holy Liturgy at the "Saint Marina" church in the city. The celebration program includes a swimming marathon and the consecration of a festive table. The festivities will culminate in a concert at the "Apolonia" summer theater, with Vice President Iliana Yotova in attendance.