AN ADVENTURER from Hampshire has completed a once-in-a-lifetime challenge by walking across the world’s largest frozen lake.

Dr Ash Routen had to endure temperatures of -35 degrees as he and fellow walker Phil Sturgeon completed a gruelling 630km trek across Lake Baikal in Siberia.

The route taken by the two men was equal to walking from London to Edinburgh or doing 15 back-to-back marathons.

Dr Routen, 31, said: “We had a truly amazing experience. The extremes of weather and the creaking and groaning of the ice on Lake Baikal were mind-blowing.

“It’s an extremely beautiful place - and the Siberian people were so supportive.”

Describing the expedition as “difficult and humbling” he added: “We now know a lot more about ourselves and our own capabilities.

“It’s incredibly satisfying to have pulled off the trip. It took about nine months of planning so to get to the start line, have a great time and come back safe and well feels pretty good.”

The two men began their 19-day journey at Listvyanka.

They walked along the western edge of the lake before negotiating Olkhon island, and finishing in Severobaikalsk. From there they took a two-day train journey across Siberia to the city of Irkutsk and back to their departure point.

Walking for between eight and 12 hours a day, Dr Routen and his companion had to cope with bone-numbing cold.

They consumed about 5,000 calories a day to give them the strength to each pull two sledges loaded with all the supplies needed to complete their journey.

During the expedition they walked across large areas of ice devoid of snow cover as well as negotiating small sections of open water.

Accommodation came in the form of remote huts, one of which was repeatedly circled by a bear. The animal was scared off with gunfire by a local ranger.

Dr Routen lived in Ringwood between 1986 and 2004, when he left to study at Exeter University.

He now lives in Leicester but his parents still reside in the New Forest and he has many friends in the area.

Baikal, the largest freshwater lake in the world in terms of volume, contains more water than the US Great Lakes combined. It is also thought to be the oldest and deepest lake on the planet.

Dr Routen’s expedition was supported by veteran polar explorer Geoff Somers.

He said: “The area is remote and challenging, and small independent trips such as this are important to raise the aspirations of young people today, and keep alive a sense of adventure.”