Children with balloons play beside the statue of British comedy legend Eric Morecambe on January 16, 2012 in Morecambe, England. According to scientists January 16, 2012 was “Blue Monday”, the most depressing day of the year. (Photo by Christopher Furlong/Getty Images)

Revellers celebrate “Ash Monday” by participating in a colourful “flour war”, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter,in the port town of Galaxidi, Greece, February 27, 2017. (Photo by Alkis Konstantinidis/Reuters)

Teeming with images of spectacular underwater scenes from around the world, Call of the Blue is the culmination of a five-year project by the photographer and ocean conservationist Philip Hamilton. This groundbreaking book includes contributions from acclaimed scientists and ocean “guardians”, who reveal what drove them to answer the call of the blue. (Photo by Philip Hamilton/The Guardian)

Students from St Andrews University indulge in a tradition of covering themselves with foam to honour the “academic family” on the lower college lawn on October 23, 2017, in St Andrews, Scotland. (Photo by Jeff J. Mitchell/Getty Images)

Revellers celebrate “Ash Monday” by participating in a colourful “flour war”, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter, in Galaxidi, Greece February 19, 2018. (Photo by Alkis Konstantinidis/Reuters)

A general view of the residential area is pictured during dusk at Jodhpur in Rajasthan, April 5, 2015. Jodhpur, also known as the blue city in the desert Indian state of Rajasthan, which residents say originally, was used to show where the highest caste of priestly Hindus live, who wanted to set them apart from the rest of the population. Later the rest of the population followed suit. Another reason for the city to be blue is to keep the buildings cool during the summers, local residents said. (Photo by Adnan Abidi/Reuters)

A relative of a Chinese passenger aboard the Malaysia Airlines MH370, covers his face after being told the latest update in Beijing, China, Monday, March 24, 2014. A new analysis of satellite data indicates the missing Malaysia Airlines plane crashed into a remote corner of the Indian Ocean, Malaysian Prime Minister Najib Razak said Monday. The news is a major breakthrough in the unprecedented two-week struggle to find out what happened to Flight 370, which disappeared shortly after takeoff from Kuala Lumpur to Beijing with 239 passengers and crew aboard on March 8. (Photo by Ng Han Guan/AP Photo)