A 15-year-old Grade 8 pupil who went for a swim with friends on his off-exam day was found dead in a quarry in Klipfontein, near Tembisa.
The incident happened on Monday at about 10am.
Morapedi Seobo, a pupil at Education Arise College in Johannesburg, had not gone to school because he was not writing exams that day.
It took more than two hours for police divers to find his body at the bottom of the quarry.
The boy's sister Nkele Seobo, 22, described her brother as a sweet, jolly and helpful child.
Constable Joyce Setshedi confirmed the young Morapedi's death.