I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission not required.
Numerous trails and paths crisscross park which features both coastal and woodland scenery. The park is easily accessed from Crawfordsburn, Helen's Bay and the North Down Coastal Path from Bangor. There is extensive (free) parking and there is a café and toilets. (Please note that DJI drones will give you a Geo Zone warning, but will not prevent flying).
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 23/09/2021. It remains the responsibility of any pilot to check for any changes before flying at the same location.