Russian Emergency Situations employees help a girl to bath in the icy water on Epiphany at the Church of the Holy Trinity in Ostankino near TV Tower in Moscow, Russia, Friday, January 18, 2019. Across Russia, the devout and the daring are observing the Orthodox Christian feast day of Epiphany by immersing themselves in frigid water through holes cut through the ice of lakes and rivers. Epiphany celebrates the revelation of Jesus Christ as the incarnation of God through his baptism in the River Jordan. (Photo by Alexander Zemlianichenko/AP Photo)

Valentyna Konstantynovska, 79 years-old, holds a weapon during basic combat training for civilians, organized by the Special Forces Unit Azov, of Ukraine's National Guard, in Mariupol, Donetsk region, eastern Ukraine, Sunday, February 13, 2022. The United States is evacuating almost all of the staff from its embassy in Kyiv as Western intelligence officials warn that a Russian invasion of Ukraine is increasingly imminent. (Photo by Vadim Ghirda/AP Photo)

Girls in red neckerchiefs dance on Red Square, with the GUM, the State Department Store and the Historical Museum in the background, during a ceremony to celebrate joining the Pioneers organization and 100th anniversary of the All-Union Pioneer Organization, in Moscow, Russia, Sunday, May 22, 2022. Pro-Communist Russians are trying to preserve the Young Pioneers, which used to be the Communist league for pre-teens in the Soviet Union. (Photo by AP Photo/Stringer)

Tupolev Tu-142MK, a Soviet and Russian maritime reconnaissance and anti-submarine warfare aircraft flies above a statue of Soviet Union founder Vladimir Lenin during a rehearsal of the Naval parade in St.Petersburg, Russia, Thursday, July 28, 2022. The celebration of Navy Day in Russia is traditionally marked on the last Sunday of July and will be celebrated on July 31 this year. (Photo by Dmitri Lovetsky/AP Photo)

Medical staff in Belgrade, Serbia on February 5, 2021. Vaccination of employees in the city's social protection institutions has begun at the Belgrade Fair, who have expressed interest in receiving the Russian Sputnik V vaccine, and according to the city secretary for social protection Natasa Stanisavljevic, about 150 employees in those institutions will receive the vaccine today and tomorrow. (Photo by Zoran Zestic/Tanjug)

A Russian Rosguardia (National Guard) servicemen secures an area as a massive blaze seen over the Crocus City Hall on the western edge of Moscow, Russia, Friday, March 22, 2024. Several gunmen have burst into a big concert hall in Moscow and fired automatic weapons at the crowd, injuring an unspecified number of people and setting a massive blaze in an apparent terror attack days after President Vladimir Putin cemented his grip on the country in a highly orchestrated electoral landslide. (Photo by Dmitry Serebryakov/AP Photo)

A Ukrainian serviceman who fought in Debaltseve is seen near Artemivsk February 19, 2015. Fighting raged in eastern Ukraine on Thursday despite European efforts to resurrect a still-born ceasefire, a day after pro-Russian separatists who spurned the truce forced thousands of government troops out of a strategic town. (Photo by Gleb Garanich/Reuters)

Lake Baikal is the world's oldest lake, at 25 million years (possibly older), and deepest, averaging 744.4 metres (2,442 ft).

Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water.