The sunken ferry Sewol sits on a semi-submersible ship during its salvage operations at the sea off Jindo, South Korea, in this handout picture provided by the Ministry of Oceans and Fisheries and released by Yonhap on March 26, 2017. (Photo by Reuters/Yonhap/The Ministry of Oceans and Fisheries)

Elley Dann indulges in some sunbathing in Primrose Hill, London on June 24, 2020, after the UK officially recorded its warmest day of the year so far when the temperature reached 32.6C (90.7F) at London's Heathrow Airport at 2.46pm. (Photo by Evening Standard/The Sun)

People take part in a traditional mid-summer solstice night celebration (Rasos Festival) at the Open-Air Museum of Lithuania in Rumsiskes, east of Kaunas, Lithuania, on late June 23, 2020. (Photo by Petras Malukas/AFP Photo)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

Young Slovaks dressed in traditional costumes throw a bucket of water at a girl as part of Easter celebrations in the village of Trencianska Tepla, Slovakia, April 9, 2012. Slovakia's men splash women with water to symbolize youth, strength and beauty for the upcoming spring season. (Photo by Samuel Kubani/AFP)

Timbuktu: A UN peacekeeper from Burkina Faso stands guard at the Djinguereber mosque, built in the 14th century, during a visit by a UN delegation on election day in Timbuktu, Mali, July 28, 2013. (Photo by Joe Penney/Reuters)

A picture made available on 08 July 2015 showsa lightning strikes during a heavy storm over Poznan in the night of 07 July 2015. Severe storms passed last night over Poland causing lots of damages to buildings, trees, electricity and railway tractions. (Photo by Lukasz Ogrodowczyk/EPA)

A girl uses her mobile phone during the evening at the National Park in Khartoum, Sudan, April 24, 2015. (Photo by Mohamed Nureldin Abdallah/Reuters)