Call for footage of Sydney boat tragedy

It is hoped video footage taken by witnesses will help investigators determine what led to a boat capsizing in southern Sydney and the deaths of three men.

Emergency services were called to Henry Head Lane at La Perouse about 12.30pm on Sunday following reports a boat had capsized near the lighthouse.

Three men were retrieved from the water but they were unable to be revived.

They have not been formally identified but are believed to be a 53-year-old man from Blakehurst, a 62-year-old man from Lilli Pilli, and a 65-year-old man from Kogarah, NSW Police said in a statement on Monday.

Detective Acting Inspector Mick O'Keefe said police were appealing for anyone who recorded video of the incident to come forward.

"We understand there were a large number of witnesses who were using their mobile phones to take video recordings of the incident and rescue," Det Acting Insp O'Keefe said in a statement.

"While detectives are still piecing together the circumstances of this tragedy, it is hoped video footage may help put those events into context."

A report will be prepared for the coroner.