Marinka’s name day is July 17, the feast of Marina the Great Martyr.
Churches that follow the Old (Julian) Calendar keep the same feast on July 30 of the civil calendar. See everything commemorated on July 17.
The saint behind the name

Marina the Great Martyr
July 17, Martyr, Μαρίνα η Μεγαλομάρτυς
St. Marina the Great Martyr was born in Antioch of Pisidia in the third century. Losing her mother as a child and raised in the countryside, she embraced Christ in her youth; when her faith became known she was seized during the persecutions, and though only about fifteen years of age she withstood interrogation, torture, and, according to tradition, the assaults of the evil one, whom she overcame by prayer, before being beheaded.
Also celebrating on July 17
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.