Russians boldly go to the bottom of the world's deepest lake

Russian scientists travelling in twin mini-submarines yesterday reached the bottom of Lake Baikal in eastern Siberia. The daring underwater mission lasted five hours and attempted to set a new world record for a manned dive in freshwater.

Two teams of three scientists piloted a pair of mini-submarines to the bed of Baikal 1,580m (5,183ft) below the surface of the lake – but fell well short of the 1,680m maximum depth that the crew had hoped to reach to break the record.

Lake Baikal is the deepest lake in the world and holds the largest body of unfrozen freshwater, so it was disappointing that the scientists had failed to reach its deepest point.

The expedition was led by Artur Chilingarov, a pro-Kremlin member of parliament and Arctic explorer who led the submarine team that controversially planted a Russian flag on the sea bed below the North Pole last August.

Mr Chilingarov said just before the mission that the aim of the record-breaking attempt to reach the bottom of Lake Baikal was to preserve the unusual habitat of the lake, which was declared a Unesco World Heritage Site in 1996 because of its unique and rare wildlife.

The 18-tonne mini-submarines, Mir-1 and Mir-2, which already hold the world record for a manned dive in seawater, had to shed weight to make them less buoyant in freshwater. The mission went well even though Mr Chilingarov had anticipated difficulties. "There are technological problems, fickle weather conditions. Freshwater dictates special conditions," he had said before the expedition.

Afterwards, Mr Chilingarov, who oversaw the operation from a mission control point on the Metropolia Platform on the lake, admitted: "There was no record. But we'll continue exploration."

Natalia Komarova, who was the first woman to take part in a Mir mini-sub dive, explained that the results of the mission, which will involve about 160 dives over the next two years, will have an important impact on enviromental legislation to protect this part of east Siberia as it undergoes intensive economic development. "We need to understand how to protect Baikal and use it without harming its unique ecosystem," Ms Komarova told reporters who witnessed yesterday's dive.

At more than 25 million years old, Lake Baikal is the oldest lake in the world. It was formed in a rift valley by the inflow of more than 350 rivers, but it is drained by just one river – the Angara.

Lake Baikal holds more water than the Great Lakes of North America combined – a volume estimated at 23,600 cubic kilometres. An unmanned submersible named Pisces reached a depth of 1,410m in 1977, during a mission when Soviet scientists examined the lake's bed with searchlights. However, the latest manned mission represents another prestige boost for a resurgent Russia after the post-communist collapse of its economy.

Lake Baikal, known as the blue eye of Siberia, is considered one of the natural wonders of the world, holding about 20 per cent of the world's unfrozen freshwater, which is kept crystal clear by tiny, filter-feeding shrimps known as epishura. In winter, when the lake's surface is frozen, it is possible to see 40 feet down into the lake.

Baikal supports more than 2,500 species of animals and plants, and 80 per cent of its animal life is endemic – including the mysterious Baikal freshwater seal which has lived on the land-locked lake for many thousands of years despite being hundreds of miles from the nearest coast.

There have been several threats to the lake over the years, starting with a paper and pulp mill built on its banks in 1996 which belched out noxious gases that killed nearby trees and released toxic chemicals into the water.

More recently, there was a plan to build an oil pipeline close to the lake but this was switched to a more distant route after a high-profile intervention by President Putin, who had promised to preserve the lake's pristine habitat.