John Bennett's farm is one of the last parcels of land standing between the deadly Currowan bushfire and the New South Wales coastal town of Nowra.

Key points: John and Merv Bennett have been working to contain smouldering peat on their farm south of Nowra

John and Merv Bennett have been working to contain smouldering peat on their farm south of Nowra Peat can be a highly combustible and unpredictable fire hazard as it allows fires to smoulder underground for extended periods

Peat can be a highly combustible and unpredictable fire hazard as it allows fires to smoulder underground for extended periods The fires have also been driving snakes off the property and toward the township

The farm is under direct threat from the fire front to the south, but alarmingly the property is on swampland and a large underground fire is already burning in the bog's peat layer.

"If the fire gets into the swamp grass, it will be impossible to put out," Mr Bennett said.

When peat burns, it can burn deep underground for metres, even in damp conditions.

Wind gusts send oxygen to the underground fire and create flames on the surface.

The underground peat fires on the farm regularly flare up. ( ABC News: Jessie Davies )

Battling to prevent flare-ups

Along with his father Merv, 75, Mr Bennett has been working around the clock extinguishing flare-ups on their property boundary.

It is exhausting work.

"The more we can do the better, because it means the Rural Fire Service trucks can keep doing what they're doing," Mr Bennett said.

John and Merv Bennett have been establishing containment lines to protect their property. ( ABC News: Jessie Davies )

This week Shoalhaven City Council established deep containment lines around the property using heavy machinery.

Waterbombing aircraft are also closely monitoring the area.

John Bennett is using a mobile firefighting unit to extinguish spot fires. ( ABC News: Jessie Davies )

A near miss

Two days ago a large fire flared but John and Merv were able to contain it.

"There was a moment when the wind turned around and all of a sudden it felt like I was going to choke," he said.

"It just got away in the blink of an eye."

Merv Bennett has been slashing tall reeds growing in the peat bog. ( ABC News: Jessie Davies )

Snakes alive

The Bennetts' farm first came under threat from bushfires on December 22.

Since then, snakes, spiders and other wildlife have been emerging from the swamp and escaping towards Nowra.

"Mother Nature knows what's happening and they're getting out of here," Mr Bennett said.

Multiple snakes have been found dead on the farm, while many others have been driven out by fire. ( Supplied: John Bennett )

In the past week the family had two dogs suffer snake bites.

RFS fire prediction maps show the Currowan fire may spread to Nowra on Saturday, fanned by hot dry westerly winds.

The Bennetts will have all hands on deck to protect their farm and, by extension, the Nowra community.

"We can only do our best," Mr Bennett said.