Thulani Sithole, 18, a pupil at the Inyamande High School, was among a group of 50 pupils on a day visit to the area at the weekend.
According to a witness, some of the school boys consumed alcohol, and then, at about 3.30pm, shortly before the group would have left the area, Sithole climbed over the viewing platform and stood on the edge of the precipice, the Beeld reported.
He lost his balance and fell to his death in front of a friend, Devine Slauwe, 18.
Rescue workers were summoned, but because it was getting dark, they were not able to retrieve Sithole’s body until Sunday morning.
The Mpumalange education department said on Sunday it would investigate the tragedy, in order to draw up guidelines to ensure that pupils were safer during school outings.