SHIMNA Integrated College principal Steve Pagan said he was "very concerned to hear about the challenges facing the outdoor centre which has been “a fantastic resource” down the years for many schools.
He said the centre facilitated practical activities as part of examination courses, supporting Shimna’s extra-curricular programme and providing essential staff training for the Duke of Edinburgh Award.
“It is a tremendous asset,” he added.
Kath Maguire, who trained as an instructor at the centre and is founder of The Feel Good Factor, a multi-sports club for women, said her group had "really missed" the facility.
She described the Tollymore staff team as “exceptional and supportive” to her business for over a decade and it was disappointed at the redundancies for staff.
"We are hopeful that a solution will be found to help this fabulous resource in the heart of Mourne thrive,” she continued.
"I have been an instructor for 25 years, since getting my qualification there. Hopefully, this will not see the centre closed on a permanent basis and it will be brought back stronger and much better used."
Ms Maguire said the club had been invited to take part in the Sport NI review.
"I have sent an email to Sport NI saying I am concerned," she added. "It is a facility we love and our community hub."
Maxi Scullion, secretary of Gilford Youth Climbing Club, said she was disappointed, describing the Tollymore centre as "a brilliant and unique place".
She said more than 50 members had stayed at the facility two years ago and participated in a range of activities.
"We slept in the accommodation, used the climbing wall and high ropes, and also had some food there," she said. "They supplied instructors to help with the climbing wall and the high ropes course that we did.
"We had a great time, a lot of the children in our group had never done a high ropes course before.
"The feedback was hugely positive, it was brilliant."