An accidental fire has virtually destroyed vegetation on an island on Lake Tekapo.
Police say the fire was started by three British construction workers, who were camping there, and quickly grew to engulf the entire island, consuming 100 year-old pine trees.
Police say it's unclear how the fire started but think it may have been from a cigarette butt.
The three men tried to put it out, but could not and were forced to flee the flames on their boat. They were then swamped by waves and had to be rescued by a local boatie.
Senior Constable Brent Swanson said the trio won't face criminal charges but the Department of Conservation may try to recover the cost of fighting the fire.
"Most of the island has probably been destroyed vegetation-wise which obviously is pretty disappointing for locals and holiday makers that use the island on a regular basis."
Mr Swanson says the fire is still smoldering on Sunday but given it's surrounded by water there is no risk of it spreading.