The mysterious message that read “help” on an isolated West Coast beach has been revealed as a youngster’s prank.

Police confirmed this afternoon the word was written on the bank of Lake Ahaura on the West Coast, east of Greymouth, by two young people.

A preventive visit would take place, police said, and their families had been talked to.

Last Friday, a passing helicopter spotted the message and on Saturday afternoon a police spokeswoman said the team had conducted a search of the area and found nothing of significance.

Lake Ahaura is at least 58km from Greymouth and about 8km from the reclusive Gloriavale Christian Community in Haupiri, the nearest settlement.

The lake is surrounded by dense bush and mountains.