Depending on your desire may include,
Hiking, Climbing, Riding, overnight in a hostel in the countryside in the hills of Olympus, or overnight in a small shelter at an altitude of 2450m with fireplace.
more details about the shelter/hut here

Hiking/climbing can be done in 3 peaks. Top Skolio & Skala about 2.900m suitable for beginners and families.
 
Mytikas (summit of Olympus 2.918m) for middle / advanced climbers