Police officers on patrol in central Oamaru on Sunday afternoon noticed water splashing out of a "very rough" looking vehicle as it drove over a speed bump on Thames St.
The officers stopped the vehicle and discovered tarpaulins forming a pool filled with warm water between the back and front seats in which the passengers, aged from their late teens to early 20s, were sitting.
"I think they were just having a bit of fun. They didn't think there were any majors with it," Sergeant Tony Woodbridge said.
The roof of the Mitsubishi saloon had been cut off and the car had been modified "quite majorly".
The driver was prosecuted for various breaches of traffic law and the vehicle was ordered off the road.
The police officers then followed it at low speed to the owner's home.
"When they opened the [car] doors at the home address, it was like a flash flood, with water coming out," Sgt Woodbridge said.
The young men were polite and accepted it was a silly thing to do, but they just did it for a laugh.
The owner planned to scrap the vehicle, the officers involved said.
The officers, who had 19 and 20 years' policing experience, had never seen anything like it before, Sgt Woodbridge said.
