This handout picture released by the Gagarin Cosmonauts' Training Centre on October 17, 2023 shows Marina Vasilevskaya (L) flying during a parabolic flight aboard a zero-gravity simulator, a Russian IL-76 MDK aircraft used for cosmonauts' training flights in weightlessness, in Star City outside Moscow. (Photo by Pavel Shvets/Gagarin Cosmonaut Training Center/AFP Photo)

Igor, a 40 year-old Ukranian soldier embraces his wife in front of his military basement in the center of Odessa on March 17, 2022. Odessa, which Ukraine fears could be the next target of Russia's offensive in the south, is the country's main port and is vital for its economy. But the city of one million people close to the Romanian and Moldovan borders also holds a special place in the Russian imagination. (Photo by Bulent Kilic/AFP Photo)

A person waves a drum while other people wearing traditional Russian village-style clothes celebrate the summer solstice near a bonfire in the village of Okunevo, about 200 kilometers (about 125 miles) northeast of the Siberian city of Omsk, Russia, on Wednesday, June 21, 2023. The festivities of Ivan Kupala, or John the Baptist, are similar to Mardi Gras and reflect pre-Christian Slavic traditions and practices. (Photo by Evgeniy Sofiychuk/AP Photo)

A runner takes part in the International World's coldest marathon at minus 53 degrees (–63.4 Fahrenheit) near Oymyakon, the republic of Sakha, also known as Yakutia, Russian Far East, Saturday, January 22, 2022. Sixty five runners, including athletes from the United Arab Emirates, United States and Belarus, started the run at extremely low temperature in Oymyakon, Yakutia's Pole of Cold. The international team of men and women ran full distance and half-marathon. (Photo by Ivan Nikiforov/AP Photo)

A young woman holds a weapon during a 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)

A Ukranian soldier hugs his wife in the city of Irpin, north of Kyiv, on March 10, 2022. Russian forces on March 10, 2022 rolled their armoured vehicles up to the northeastern edge of Kyiv, edging closer in their attempts to encircle the Ukrainian capital. Kyiv's northwest suburbs such as Irpin and Bucha have been enduring shellfire and bombardments for more than a week, prompting a mass evacuation effort. (Photo by Aris Messinis/AFP Photo)

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.

ESA astronaut Paolo Nespoli looks on after landing back on Earth from their Soyuz TMA-20 spacecraft on May 24, 2011 in Zhezkazgan, Kazakhstan. The mission of the Soyuz TMA-20 was launched last December to the International Space Station with the flight engineers Catherine Coleman from the United States, Russian cosmonaut Dmitry Kondratyev and Italian astronaut Paolo Nespoli. The next expedition is expected to launch this June. (Photo by Stephane Corvaja/ESA via Getty Images)