The neonate sperm whale appeared on a rocky beach at Little Garie in the Royal National Park on Tuesday.

Read more: Bigger than Ben Hur': after hours rescues at North Gong out of control

A spokeswoman for the NSW National Parks and Wildlife Service confirmed the four-metre whale was deceased.

She said they were first alerted around 10:30am on Tuesday with staff subsequently attending the site.

Volunteers from ORCCA (Organisation for the Rescue and Research of Cetaceans in Australia) were also contacted.

"ORCCA volunteers assisted to collect further photographic information and took measurements to assist with research," the NPWS spokeswoman said.

"The whale was washed up dead on the beach and is in a moderately advanced state of decay.

"The carcass is on a remote beach with access only possible on foot in the current conditions."

Read more: Koonawarra man faces court accused of kidnapping and robbery

She said the NPWS would continue to monitor the carcass but no further action would be taken at this stage, given its location.

The Illawarra Mercury newsroom is funded by our readers. You can subscribe to support our journalism here.