Prime Minister Malcolm Turnbull has been slapped with a fine after he was caught not wearing a life jacket while on board a dinghy.

Mr Turnbull was photographed without the jacket while moving the dinghy near his Sydney harbourside residence earlier this week.

The executive director of NSW Maritime, Angus Mitchell, confirmed Mr Turnbull would be sent a $250 fine.

A spokesman for the Prime Minister said the penalty notice would be paid as soon as it is received.

Mr Mitchell said it was a timely reminder during the holiday season to always wear a life jacket.

"With a fatality this morning just off Botany Bay, NSW Maritime officers will be out in force during the New Year period to ensure all boaters are adhering to maritime safety laws," he said in a statement.

"We want to ensure everyone enjoys their break and gets home safely this summer so please, wear a life jacket and take care on our waterways."

Mr Turnbull apologised on Thursday, saying water safety was important at this time of year and NSW Maritime had explained "technical" rules to him.

"So lesson learned; I will make sure I always wear a life jacket in my dinghy regardless of how close I am to the shore, just as I always do on my kayak," he said.