Russia's Prime Minister Vladimir Putin (L) climbs onboard a "Mir-2" mini-submersible on Lake Baikal August 1, 2009. Putin dived into the depths of Lake Baikal aboard a mini-submersible on Saturday in a stunt that adds a new dimension to his carefully cultivated macho image. The judo black belt -- who has already conquered the skies in a fighter aircraft and shot a Siberian tiger in the wild -- will descend 1,400 metres (4,600 ft) below the surface of the world's deepest lake to inspect valuable gas crystals. [Chinadaily.com.cn via agencies]

Macho image

The 56-year-old former KGB spy has cultivated his macho image, and polls show this has won him many admirers, especially among Russian women.

In 2007, while president, he featured in magazines across the world after donning combat trousers stripped to the waist while on a fishing trip in the Yenisei River.

Since stepping down from the Kremlin last year to become prime minister, Putin has remained in the public view.

Sensitive to Russia's growing environmental movement, Putin while president changed the route of a planned oil pipeline to avoid Lake Baikal, which contains one fifth of the world's unfrozen freshwater.

Scientists are studying the formation of hydrate masses deep beneath the lake and searching for economically viable ways to extract trapped gas from the crystals since existing technologies are too expensive.

"In 50 years, when other energy sources end, people will have to look into gas extraction from hydrates," said Oleg Khlystov, a scientist with the Lake Studies Institute, who said his team had found a cheaper method and applied for a patent.

Khlystov said Russian gas firm Gazprom was not interested in the new technology but that he had hopes for it in the future. "If Putin is interested, we will tell him (about it)," he said.

Khlystov's $8.5 million two-year mission studying the lake's depths has performed 96 dives. Last year, it set a world record for freshwater submersion by descending 1,680 metres to the lake's deepest point.