The ski slopes surrounding Thredbo were silent on Saturday night as hundreds of skiers lit up the snow to commemorate the 20th anniversary of the village's devastating landslide.

Eighteen people were killed and two ski lodges destroyed when 1,000 tonnes of mud and debris cut a devastating path through the Snowy Mountains community just before midnight on July 30, 1997.

The instability of the area hampered the enormous rescue operation, with emergency workers having to operate on a very steep slope, taking care not to cause any further landslides.

Incredibly, one man, Stuart Diver, was pulled from the rubble alive after being trapped under three concrete slabs for 65 hours, next to the body of his wife.

It was Australia's worst landslide disaster.

Twenty years on, about 300 skiers navigated Thredbo's snow-covered tracks creating a snaking line of red lights as part of a flare run, which was seen as a fitting tribute for those who loved the mountains.

To honour the victims, 18 flares were planted on the slopes and the same number of fireworks later rang out above the village.

While not a word was spoken during the descent, many participants described the occasion as emotional, before catching a chairlift to the mountain's peak.

"A lot of my friends were in the landslip and I'm here to commemorate them and think about what happened that night," Tim Robertson said.

Candy Thompson said she had travelled to Thredbo many times over the years, but this trip was particularly special.

"I think it's terribly important as a memorial to the people who died and also looking forward into the future," she said.

"It [is] emotional thinking of that terrible disaster."

Standing room only at church service

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While the village has been rebuilt and once again supports dozens of tourism businesses, many people who were there on the day are still dealing with the tragedy.

On Sunday, the official anniversary of the disaster, there was standing room only at the Thredbo church service to pay respects to the victims and reflect on how the community had recovered.

A bell outside the church tolled 18 times, one for each victim of the landslide, while inside their names were read aloud to the congregation.

Many people who attended the service, some of whom had lost friends and family in the tragedy, remarked that the occasion was a time to remember those lost and reflect on how those left behind were still dealing with the disaster.