Tonic Health Club at Castleknock Hotel has reopened this year after its closure due to building works and is now bigger and better than ever. Tonic Health Club now has a new aerobics studio on the ground floor, double the size of the previous 1st-floor room, and located right beside the fitness centre. A range of new equipment and a new floor have also been added to the fitness centre, along with a complete refurbishment of the changing room showers, toilets, and wash areas.