Abseiling
The quiet Kaaimans Canyon has one of the most beautiful Abseiling options and you get the opportunity here over 2 x 45 meters next to a beautiful waterfall. The first part is easy for them to get used to the feel of the abseiling and rope. The second part is technically more demanding and they will be impressed.
Another highlight is that they reached the bottom land in a canoe.
Even without previous rappelling or climbing experience you can enjoy this experience here on the Garden Route, but a certain amount of physical fitness is a prerequisite and it's not for people with weak nerves or fear of heights. You should also wear no slippery shoes.