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.

Model enthusiast Peter Smith poses with his collection of handmade scale model coaches at the “London Model Engineering Exhibition” at Alexander Palace on January 20, 2012 in London, England. (Photo by Dan Kitwood/Getty Images)

Wanwisa, a Lao Yi Lai Heng Chinese opera performer waits backstage at the Plub Plachai temple on January 25, 2012 in Bangkok, Thailand. The traditional Chinese art form involving music, singing, martial arts and acting has a history of more than 500 years. There are about 30 members working with the group doing specials shows all week to celebrate the Chinese New year. The Chinese opera is popular in many parts of China, Malaysia, Singapore, Thailand and Macau. (Photo by Paula Bronstein/Getty Images)

A series of beautiful shots of divers swimming near sunken ships have emerged. Alex Voyer, 39, was sailing around the Caribbean on a 60-foot boat when he stopped for a dive. The images show amazing shipwrecks as free divers explore the seabed. Here: A diver swims in the shallow water under a pier. (Photo by Alex Voyer/Caters News Agency)

The British Breitling Wingwalkers, Danielle Hughes and Emily Guilding, soar above the Palm Jumeirah in Dubai at 1,500 feet (460 meters) in excess of 100mp/h, ahead of their Dubai debut performance at the 2014 UIM Skydive Dubai XCAT World Powerboating Series, on Saturday, 13th December 2014. The British team is the only aerobatic formation display team who employ full time wingwalkers and fly their two Breitling-liveried 1930's Boeing Stearman bi-planes at Air Shows and major sporting events around the world. (Photo by Katsuhiko Tokunaga/Breitling via AP Images)

A soldier poses with a Hythe Mk III Gun Camera during training activities at Ellington Field, Houston, Texas in April of 1918. The Mk III, built to match the size, handling, and weight of a Lewis Gun, was used to train aerial gunners, recording a photograph when the trigger was pulled, for later review, when an instructor could coach trainees on better aiming strategies. (Photo by Harry Kidd/WWI Army Signal Corps Photograph Collection via The Atlantic)

Chinese artist Song Dong stands in his installation entitled “Waste Not” in The Curve at the Barbican Art Gallery on February 14, 2012 in London, England. Waste Not comprises over 10,000 objects collected by Song Dong's mother over a period of 5 decades. The installation is Song Dong's first major solo exhibition in the UK and opens to the general public on February 15, 2012. (Photo by Oli Scarff/Getty Images)