The family of an Australian man who disappeared off a Bali beach while trying to rescue a swimmer is pleading for help.

Craig Laidley was walking along Balian Beach in Tabanan, on Bali's mid-west coast on Wednesday afternoon, when he heard the shouts of a young German swimmer who had been swept away in rough seas.

After managing to save the 29-year-old tourist, the 56-year-old was then himself carried away by the current.

Relative Jayke Laidley posted a plea on social media for assistance from the public.

"Our Uncle/Brother and Son (Craig) was last seen helping a male that was reportedly drowning in the ocean between Tebing Balian rocks near Balian Beach [on Wednesday] at 4pm 16th of October," he wrote.

"Any assistance would be greatly appreciated."

Search and rescue teams have been scouring the land and sea for signs of Mr Laidley, as hopes fade of finding him alive.

"[On Wednesday] night our team tried to search for victims using land searches and today the Denpasar Search and Rescue Office dispatched 10 people with land and sea SRU divisions," said Nyoman Sidakarya, the head of the Denpasar Search and Rescue Office.

He said rough seas had hampered search efforts.

"Information from the team at the location is that the wave conditions are extreme and the search is currently being carried out by land SRU," he said.

Another spokesperson from the search and rescue agency Basarnas I Gusti Ayu Yanti told ABC News they had not given up on finding Mr Laidley alive.

Witness Wayan Sudarma said there were no warning signs around the beach, despite the dangers.

"Incidents like this happen often here," he told the ABC.

"About four months ago, a foreigner went missing. He was found dead 4 hours later."

"In the last five years, there have been five incidents like this."

According to police, Craig Laidley lives in Bali but is originally from Perth.

The search is set to continue on Friday morning.