It's been 21 years since the educational facility was launched in town with six students.

And, in February 2018, it became part of the Pacific Group of Schools - and changed its name.

David O'Hara, who took on the role of principal in 2015, said the school had experienced "dramatic growth", courtesy of the new branding.

"There were 24 students two years ago and there are 68 today," he explained.

"In 2020, we've started Year 7 as well.

"This is an exciting development as part of our Middle School project.

"In 2021, we'll be adding Year 8 and Year 9 the following year.

"Then, in 2025, Pacific Brook will boast its first Year 12 students and HSC graduates."

The special anniversaries were acknowledged with an assembly, which included presentations by the pupils, recollections of the school's journey by long-term parents and students, a two-layer cake, and a time capsule containing the youngsters' work which will be dug up in 2025.

"We have invested in land here in town so that we can expand the school even further," Mr O'Hara said.

"It will have to go through a government rezoning process before we can start building.

"But, it is a very exciting time for the school and we look forward to the future."