Police are seeking information about a man who performed an act of indecently in view of two boys at Warrawong on Friday.
The boys, aged 11 and 14, were fishing from a board walk 100 metres west of the Illawarra Yacht Club on Northcliffe Drive, about 2pm.
They have told police the stranger tried unsuccessfully to engage them in conversation, then stood a short distance away and committed an act of indecency.
The boys ran home and told their parents, who contacted police.
Police from Lake Illawarra Local Area Command searched the area but could not locate the man, who is described as being of Caucasian appearance, 30-40 years old with an average build.
The man had a shaved head with a tuft of hair at the front, and was about 165cm tall, the boys said.
He wore a black t-shirt with black jeans and a black cap with white writing.
Police are urging anyone with information about the incident to come forward.
Crime Stoppers: 1800 333 000.