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.

“The Naval and Military Club is a gentlemen's club in London, England. It was founded in 1862 because the three then existing military clubs in London – the United Service, the Junior United Service and the Army and Navy – were all full. The membership was long restricted to military officers. This is no longer the case, but it still has a predominantly military and ex-military membership”. – Wikipedia

Photo: Members of the prestigious “In and Out Club”, one of the oldest and most exclusive clubs in London, march around St. James's Square during the club's 150th birthday celebration on March 1, 2012 in London, England. Patrons of the private members club, whose official title is the Naval and Military Club, gathered in St. James's Square in Central London before marching with the Band of the Royal Logistics Corps to be greeted by HRH The Duke of Edinburgh, and retiring for lunch inside the club. (Photo by Dan Kitwood/Getty Images)

Four hundred buyers from around the world join 260 diamond manufacturing and trading firms on International Diamond Week as some 1,500 people are expected to trade more than billion of polished diamonds this week in Ramat Gan, Israel on February 16, 2016. The Israel Diamond Exchange is considered the most secure in the world, covering an area of 100,000 square meters with 3,500 bourse members. (Photo by Nir Alon via ZUMA Wire)

In this handout image provided by Ogilvy, a burger made from cultured beef, which has been developed by Professor Mark Post of Maastricht University in the Netherlands (pictured) is shown to the media during a press conference on August 5, 2013 in London, England. The in-vitro burger, cultured from cattle stem cells, the first example of what its creator says could provide an answer to global food shortages and help combat climate change, was fried in a pan and tasted by two volunteers. The burger is the result of years of research by Dutch scientist Mark Post, a vascular biologist at the University of Maastricht, who is working to show how meat grown in petri dishes might one day be a true alternative to meat from livestock.The meat in the burger has been made by knitting together around 20,000 strands of protein that has been cultured from cattle stem cells in Post's lab. (Photo by David Parry)

Glamour model and actress Sabrina seated on the knee of Arthur Askey. (Photo by Keystone/Getty Images). 1955

Dan surrounded by seven days of her own rubbish in Pasadena, California. If you've never thought about how much rubbish you throw away an honest photographic series will open your eyes. Men, women, couples and families with young children have been photographed lying on their backs surrounded by a week's worth of their own rubbish – from old cartons of milk, used nappies and even tampons. The startling series “Seven Days of Garbage” by Californian photographer Gregg Segal is an unforgettable reminder of the amount of waste a human collects in just seven days. (Photo by Gregg Segal/Barcroft Media)

Meirav Stardinner receives a snake massage from Ada Barak at Barak's snake spa on September 11, 2008 in Talmei Elazar, Israel. Barack's income comes mostly from exhibiting her plants which eat everything from insects to small mammals. She discovered snakes' therapeutic value after letting people hold them after her act “Some people said that holding the snakes made them feel better, relaxed”, she says. “One old lady said it was soothing, like a cold compress”. Now she uses a combination of big snakes for deep massage and little ones for light massage, though all are non-venemous. (Photo by Uriel Sinai/Getty Images)

“Echus Chasma is a chasma in the Lunae Planum high plateau north of the Valles Marineris canyon system of Mars. Clay has been found in Echus Chasma that means that water once sat there for a time. Echus Chasma is approximately 100 km long and 10 km wide, with valleys ranging in depth from around 1 km to 4 km”. – Wikipedia

Photo: In this handout image supplied by the European Space Agency (ESA) on July 16, 2008, The Echus Chasma, one of the largest water source regions on Mars, is pictured from ESA's Mars Express. The data was acquired on September 25, 2005. The dark material shows a network of light-coloured, incised valleys that look similar to drainage networks known on Earth. It is still debated whether the valleys originate from precipitation, groundwater springs or liquid or magma flows on the surface. (Photo by ESA via Getty Images)