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.

Indigenous Sahrawi girls play on an improvised see-saw at a refugee camp of Boudjdour in Tindouf, southern Algeria March 3, 2016. UN Secretary General Ban Ki-moon is scheduled to visit the Sahrawi refugees in south-west Algeria's Tindouf region. (Photo by Zohra Bensemra/Reuters)

The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)

Wearing a protective mask to curb the spread of the new coronavirus a man attends a memorial for those who have died from COVID-19 worldwide, at Rio's Christ the Redeemer statue in Rio de Janeiro, Brazil, Wednesday, July 1, 2020. (Photo by Leo Correa/AP Photo)

Russia's figure skater Alexandra Trusova performs in a show at the CSKA arena in Moscow on February 14, 2023. (Photo by Kirill Kudryavtsev/AFP Photo)

Sinterklaas (R) a legendary figure based on Saint Nicholas, Christian patron saint of children, and page Sooty Piet have a video call with children in Dodewaard, the Netherlands, 01 December 2021. The Christian feast of Saint Nicholas is celebrated annually with the giving of gifts on the eve of 05 December in The Netherlands. (Photo by Remko de Waal/EPA/EFE/Rex Features/Shutterstock)

Big wave surfers on their jet skis in front of a surf of a huge wave on the rock of Sao Miguel Arcanjo fort and Nazare lighthouse during a surfing session at Praia do Norte on January 27, 2025 in Nazare, Portugal. (Photo by Stefan Matzke - sampics/Corbis via Getty Images)

Dario Sammartino, of Italy, competes at the final table during the World Series of Poker at the Rio hotel-casino in Las Vegas Sunday, July 14, 2019. (Photo by Steve Marcus/Las Vegas Sun via AP Photo)