Hyundai Sky Park, also known as Mushroom Farm Park is a small park in Sandton just behind the Radison Blu hotel. This is one of Hyundai's green environment projects in Johannesburg, they secured the rights to the park about 2 years ago and have been working to improve it and make it a more ecologically friendly park.
The park currently features an interactive play area, fitness equipment, earth garden, an amphitheater, a sky balloon ride (not that I could find anyone to pay so I could go up), and their are plans to add a coffee shop and restaurant in the future. Through all their work Hyundai has transformed Mushroom Farm Park into a quiet sanctuary in the hart of the Johannesburg central business district where families and other visitors can go and relax in a safe an (mostly) clean environment.
Personally I think they need to put a little more effort into grounds maintenance as there was trash floating in the ponds and a large trash pile behind one of the sheds (which could easily have been hidden by a fence). The other problem is the bathrooms which are right next to the parking lot smell like they had not been cleaned in a couple months, but otherwise I found the park very pleasing and will keep trying to figure out how to go up in the balloon.