The mammal noticed the good-sunny weather, so it decided to make the most of it.
The hippopotamus preferred to rest in a rather atypical way for its species, raising its legs in the air while swimming in the water.
Cilliers, 52, was visiting the reserve with his family when he spotted the huge animal.
At first, she was afraid that the hippo might be sick or injured, but it was just relaxing.
“At first I thought maybe he was in pain or bad, but it happened several times, and he constantly stood on his back for several minutes,” the woman said.
“He seems to enjoy being upside down”. The unusual sight surprised everyone, including Cilliers, who couldn’t help but laugh, as did the rest of the group, when he realized the hippo was just trying to add some tan.