An employee of the British Museum examines a silver coin dating from 900 AD which is part of the Silverdale Viking Hoard on December 14, 2011 in London, England. The hoard, which was discovered by local metal-detectorist Darren Webster in North Lancashire, comprises of 201 silver objects including arm-rings, coins, finger-rings, ingots, brooch fragments and fine wire braid. (Photo by Oli Scarff/Getty Images)

Submersible “Jiaolong” is put into the sea for the second dive during a series of six scheduled ones to attempt the country's deepest-ever 7,000-meter manned dive on June 19, 2012 in At Sea, Unspecified. The submersible “Jiaolong”, carrying three people, reportedly reached a depth of 6,965 meters in the Mariana Trench, the deepest part of the world's oceans which is located in the western Pacific Ocean, on June 19, local time. (Photo by China Foto Press)

A man paddles a makeshift boat along a flooded street in Guasdualito, in the state of Apure, Venezuela, July 4, 2015. A total of 9,000 families have been affected by the overflowing of rivers Arauca and Sarare in Guasdualito, Apure state, because of the heavy rains in recent days in this area of the country, local media reported. (Photo by Carlos Eduardo Ramirez/Reuters)

A man wearing a Guy Fawkes mask enjoys a ride on a 350-meter (1148 feet) long water slide during 2015 City Silde Festa in central Seoul, South Korea, July 19, 2015. A 350 meter-long waterslide has been installed in downtown of Seoul, the longest waterslide to be recorded in Korea, according to local media. (Photo by Kim Hong-Ji/Reuters)

Residents make their way along a fence as they try to cross a flooded street after heavy rainfall hit Wuhan, Hubei province, China, July 23, 2015. Severe downpours hit the city on Thursday, flooding streets and shutting down public transportations, local media reported. (Photo by Reuters/China Daily)

A man wearing a native costume named “Woman Carrying Husband” poses ahead of the Carnival in Sostanj January 15, 2015. Slovenians and members of various ethnological groups celebrate the annual carnival, also known locally as Pust, by wearing traditional masks and costumes to symbolically “chase away” the winter. Prust runs from February 7 to 17 this year. (Photo by Srdjan Zivulovic/Reuters)

Tacos of Cochinita Pibil, a popular dish from Yucatan, are seen during an attempt to break the Guinness World Record for the world's longest taco in Guadalajara February 15, 2015. Guadalajara broke the Guinness record for the longest taco of cochinita pibil, with a length of 2.5 kilometers, as part of the COME gastronomy festival, local media reported. For the preparation of the traditional dish, the chefs used 4 tons of pork, 36,000 tortillas and spices for 325 taco servings. (Photo by Alejandro Acosta/Reuters)

A truck remains mired in mud and debris on State Route 58 near Tehachapi, California, about 60 miles (97 km) outside of Los Angeles October 17, 2015. A mudslide on Thursday left nearly 200 vehicles, including 75 semi-trailer trucks, stuck in up to five feet of mud, local sheriff's spokesman Ray Pruitt said. (Photo by David McNew/Reuters)