NSW man dies saving boy in kayak capsize

A NSW Central Coast man has died saving the life of a young boy after their kayak capsized. (AAP)

A man has died while "heroically" saving the life of a young boy after a kayak capsize on the NSW Central Coast, emergency services say.

Paramedics were called to Gwandalan on Lake Macquarie at about 5.30pm on Friday where the man, believed to be in his 30s, had been pulled from the water by bystanders.

They gave him first aid, but he could not be saved.

"It appears the man has heroically held the young boy above the water when they've tipped over, saving his life," Inspector Andrew Craig from the NSW Ambulance said.

"Unfortunately, despite the best efforts of bystanders and paramedics, the man was unable to be revived."

The young boy was assessed by paramedics at the scene and was physically uninjured, NSW Ambulance say.