"He was very lucky. Everyone realised what was going to happen so they cut the motor and stopped it."
A retired surgeon was present at the time of the accident and tended to the boy until the Rotorua-based BayTrust Rescue Helicopter arrived.
Its paramedics stabilised the boy.
Paul Connell of Clearwater Cruises last night refused to discuss the incident, but confirmed the company was "going through a process" with marine safety authorities.
Mr Connell confirmed the youngster had received "cuts and lacerations" after "an accident with the jet-ski".
Senior Sergeant Tony Colby of Rotorua police said staff were not yet investigating the accident, but had not ruled out getting involved.
Hospital duty manager Anne Sullivan last night refused to discuss the matter - or the condition of the youngster.