Deers walk past Indonesia's honour guard as they wait for the arrival of Saudi Arabia's King Salman bin Abdul Aziz at the presidential palace in Bogor on March 1, 2017. Cheering crowds welcomed King Salman on March 1 as he began the first visit by a Saudi monarch to Indonesia for almost 50 years, seeking stronger economic ties with the world's most populous Muslim-majority country. (Photo by Adek Berry/AFP Photo)

Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

People are seen in the crowd as Serbian Emir Kusturica & The No Smoking Orchestra performs during the third day of the Mexican musicial festival Vive Latino, at the Foro Sol in Mexico City, on March 29, 2014. (Photo by Alfredo Estrella/AFP Photo)

The crowd watches as stunt pilots Melissa Pemberton, Jurgis Kairys and Skip Stewart of The Immortals fly past pyrotechnics as they perform at The Australian International Airshow on March 1, 2015 in Avalon, Australia. (Photo by Scott E. Barbour/Getty Images)

Costumed attendees participate in the Dragon Con Parade, during the annual science fiction, pop culture and fantasy convention in Atlanta, Georgia, USA, 02 September 2023. Thousands of attendees, some costumed, crowd downtown Atlanta for the annual Labor Day Weekend gathering. (Photo by Erik S. Lesser/EPA/EFE)

Jeffrey Shiau, 35, a volunteer from the crowd, spits water into the mouth of Sam Kaufman, 27, a performer from the Human Fountains, during a reopening party held as coronavirus disease (COVID-19) restrictions are gradually lifted in Los Angeles, California, U.S. June 15, 2021. (Photo by Cheney Orr/Reuters)

A surfer rides a wave as bioluminescent plankton lights up the surf around him during the coronavirus outbreak, Thursday, April 30, 2020, in Newport Beach, Calif. California Gov. Gavin Newsom on Thursday temporarily closed Orange County's coastline after large crowds were seen there. (Photo by Mark J. Terrill/AP Photo)

Every year, in the Rostov region of Russia, a group of 40 young and not so young rural workers compete in the Bison Track Show, or more affectionately known as: Russian Flying Tractor Racing. In front of crowds numbering up to 30,000 people, a series of smoke spilling, monstrous farming machines tear round an 8km mud track, plowing through lakes and dirt mounds, their turbos screaming and tyres scrabbling to find grip.