A New Year's tree on the bottom of Lake Baikal? 

Nothing seemed impossible for a trio of Russian ice swimming enthusiasts who this week put up an artificial fir tree on the bottom of the world's deepest lake to celebrate the country's holiday.

Instead of wetsuits and scuba diving gear, the trio wore just festive trunks and socks and Santa hats as they performed a brief underwater dance routine around the tree.

"We wanted to congratulate people with the upcoming New Year's holidays," 27-year-old ice swimmer and blogger Yegor Lesnoi told AFP on Friday.

The mission near the village of Sarma was "both challenging and interesting," he said.

The tree was installed near the shore, at the depth of some three meters, after the swimmers cut a hole in the thick ice.

They said the water temperature of just above 0 degrees Celsius and an icy wind did not deter them.

But even though the men have several years of experience this week's dive was particularly difficult because they had to swim under the ice, Lesnoi said.

The men said they also wanted to promote clean living.

"After the swim the plastic green beauty was lifted up to the surface so as not to pollute Lake Baikal," said Sergei Smetankin, who helped organise the dive.

The swimmers also removed several car tyres from the water, they said.