Colaiste Muire, Realt na Mara (Our Lady Star of The Sea) was opened in 1947. It provided a second level education for girls of the area and they were taught by seven Presentation sisters and one lay person. The school adopted the motto ‘Respice Stellam, Voca Mariam’ which translated means ‘Look to the star, call upon Mary’ reflecting the influence of its location in the small fishing port of Crosshaven. When the school opened there were approximately one hundred students attending.
In 1952 due to the demand for extra classrooms, a top floor was built onto the Colaiste Muire block which had been used since 1891 as a primary school. Some of these classrooms include Naomh Ide and Naomh Colmcille.
Colaiste Muire was an all-girls school until 1969 when eighteen boys started here. Prior to this boys of the locality had to travel to Cork City to receive a second level education. The school had now become co-educational and this resulted in an increase of pupils. In 1970 this increase led to an extension of the school which facilitated many specialist rooms and introduced a range of new subjects such as woodwork, Technical Drawing and Home Economics.
In 1975, a new girl’s primary school was built and so this allowed the growing secondary school to move into their rooms in the school building which they shared. The school had seen many changes but Christian values always remained at the heart of the school.
In 1981 a new sports hall was built offering excellent facilities not only for the students but for members of the local community. In September of 1986 the new programme of Transition Year began in the school.
In 1998, the school which had been a boarding school and an Alma Mater to thousands for over a century had finally phased out. The school was no longer used as a boarding school but continued as a day secondary school.
In 2008, a final change was made to the school when a new section of the school was built including new classrooms and many new specialist rooms. This allowed students to move out of the old, convent part of the school and move into a new, modern building.