The incident took place on Monday evening when Meenakshi Priya Rajesh slipped at Bandra Bandstand while taking a selfie with her sister and mother, a senior police official said.
The family had come to Mumbai for a vacation.
Miss Meenakshi's father had warned her against taking a selfie. She lost balance while clicking the selfie and was drifted into the sea, he said.
Her body was found later in the day. She was taken to hospital where doctors declared her brought dead, police added.