Buyan, a male Siberian brown bear, is given a shower by a zoo employee in his enclosure at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk June 24, 2014. The Siberian city has been experiencing temperatures of around 30 degrees Celsius over the last week. (Photo by Ilya Naymushin/Reuters)

Nigerian make-up artist, Mary Oni, creates artwork on her chest using make-up, in her home in Lagos, Nigeria on January 26, 2022. (Photo by Seun Sanni/Reuters)

A Muslim dervish sings a traditional Sufi song near a rally for the Mawlid al-Nabi holiday, marking the birthday of Islam's prophet, Muhammad, in Lahore, Pakistan, Sunday, November 10, 2019. To mark the holiday, thousands take part in religious processions, ceremonies and distribute free meals to the poor. (Photo by K.M. Chaudary/AP Photo)

A brown capuchin monkey holds a fruit in the Botanic Garden of Rio de Janeiro, Brazil, on July 5, 2013. (Photo by Pablo Porciuncula/AFP Photo)

Men from the Kenyan Maasai tribe perform a traditional jumping-ritual among fellow members of a common age-set as they observe a rite of passage to mark the transition of an age-set to cultural junior elder from Moran (Maasai for warrior age-set) at a manyatta or traditional homestead built specifically for the ceremony near Lemek town within the Masai-Mara National Reserve ecosystem in Narok county February 27, 2021. (Photo by Tony Karumba/AFP Photo)

A sacrificial goat peeks through the entrance gate of a house, ahead of the Eid al-Adha festival in Peshawar, Pakistan on June 28, 2023. (Photo by Fayaz Aziz/Reuters)

A boy runs with a burning barrel soaked in tar at the annual Ottery St Mary tar barrel festival on November 5, 2015 in Ottery St. Mary, England. The tradition, which is over 400 years old, sees competitors (who must have been born in the town to take part) running with burning barrels on their backs through the village, until the heat becomes too unbearable or the barrel breaks down, starting with junior barrels carried by children and continuing all evening with ever larger and larger barrels. The event, which has been threatened with closure on previous years due to increasing public liability insurance costs, raises thousands of pounds for charity and attracts spectators from around the world. (Photo by Matt Cardy/Getty Images)

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.