The body of a shark attack victim washing ashore, the discovery of hundreds of rounds of ammunition, and a mass evacuation during one of Australia's worst bushfires are just some of the incidents handled by Preston Beach's volunteer rangers.

The small group oversees the section of Western Australia's coastline between Myalup and Mandurah, about 120 kilometres south of Perth.

Started in 1999, the group of volunteer rangers was initially set up to deal with an increase in traffic on the white-sand beach that stretches unbroken for 17km.

Volunteer ranger Noel Dew said in the more than 20 years since the rangers began patrolling Preston Beach, there wasn't much the group hadn't seen.

A shark attack and a bushfire

In 2012, 33-year-old Peter Kurmann was diving with his brother about one nautical mile off Stratham Beach, near Busselton, when he was fatally mauled by a shark.

Less than a week later, his remains washed ashore at Preston Beach.

Mr Dew said it was a day that had stuck with him.

"I received a call from one of the shire rangers," he said.

"She'd had a call that there was an incident on the beach, and as she's talking to me she suddenly started repeating, 'Oh no, oh no'.

"We realised then, what had happened.

"We came down here as soon as we could and shut the beach down.

"It was a pretty traumatic experience for everyone, but I'm glad it hadn't been a busy day and no children were around."

The Preston Beach volunteer rangers helped to evacuate people during the January 2016 bushfires in the Waroona Shire. ( Supplied: DFES )

The rangers also played an integral role in January 2016 when a lightning strike triggered a blaze that tore through some of WA's best agricultural land, and almost wiped a small community off the map.

By the time the fire was extinguished 17 days later, almost 70,000 hectares of land had been scorched, more than 180 homes and buildings had been destroyed, and two lives had been lost.

Mr Dew said the rangers helped to evacuate hundreds of people to the beachfront, where they remained for almost two days.

"About two o'clock in the morning on January 6, we had a call to say that people needed to evacuate," he said.

"We were told the fire had jumped the road and was heading our way.

"We were fearful Preston Beach was going to go.

"At one stage we had boats coming down from Mandurah to take people to safety."

Barry Pitman of the Preston Beach volunteer rangers in the group's all-terrain vehicle. ( ABC South West: Sebastian Neuweiler )

A magnet for the unusual

Mr Dew said that while the majority of the rangers' time was spent overseeing beachgoers' safety and protecting the environment, tasks slightly left of field weren't uncommon on the beach.

"One day we had a box of ammunition, which I later found to be 308 dum-dum bullets, just wash up," Mr Dew said.

"To this day we have no idea where they came from. The whole box was in excellent condition."

On another occasion an eight tonne drum from South Africa washed ashore.

University of Western Australia Professor of Coastal Oceanography Charitha Pattiaratchi said local wind and tide conditions were most likely the cause of the unusual wash-ups.

"In the case of Preston Beach, it is most likely an area where you have accumulation of material because of the wind conditions," he said.

"It works very much like a funnel.

"There are little indentions, which are mainly due to the offshore typography with reefs and things like that.

"That's what actually determines the local current systems.

"That would help, or influence, the accumulation of material.

But it's not just inanimate objects that find their way to Preston Beach.

Mr Dew said marine life, such as whales and seals, were becoming increasingly regular visitors.

Seals and whales are increasingly showing up on Preston Beach on the WA south coast. ( Supplied: Noel Dew )

"Roughly five years ago we found a penguin just sitting down here," he said.

"It just washed ashore, slightly injured.

"We put it in a box, the angry little ant he was, and contacted the proper authorities.

"I suspect it came from Penguin Island, near Shoalwater Bay.

"They told us that sometimes the normal food source isn't as prolific as the penguins would like, and so they make their way further south. That's what we think might have happened to this fella."