The violent fire broke out at around 6pm last night, February 27, according to local media.
A number of firefighters attended the scene, alongside the police, Coast Guard soldiers and precautionary ambulance, Italian news site Riviera24.it said.
The report added that no injuries have been reported and the cause of the fire remains unknown.
Drone footage posted by Riviera24 shows the extent of the damage, with the blackened Pamela IV still smoking this morning. Firefighters can also be seen moving inside the yacht.
Delivered in 1962, the 30.57 metre Pamela IV was built by CNL Liguri and was designed by A. Pulitzer with interior design by Officine Mariotti. Accommodation on board is for eight guests and five crew members.