A instructor (2nd L) from the Philippine Mermaid Swimming Academy assists participants of a monofin swimming summer workshop as they practise floating in the water of a private pool in Paranaque city, metro Manila April 5, 2014. The Philippine Mermaid Swimming Academy workshops, which were originally conducted on the beaches of Boracay Island, central Philippines, currently cost 1,800 pesos per person ($40) for a two-hour session. (Photo by Romeo Ranoco/Reuters)

A swimmer competes during the UK Cold Water Swimming Championships at Tooting Bec Lido in south London January 24, 2015. (Photo by Luke MacGregor/Reuters)

North Korean soldiers keep watch at the bank of the Yalu River, near the North Korean town of Sinuiju, opposite Dandong in China's Liaoning province, September 10, 2016. (Photo by Thomas Peter/Reuters)

North Koreans wave as Hughes MD-500 helicopters fly past during an aerial display on Saturday, September 24, 2016, in Wonsan, North Korea. North Korea on Saturday opened an air festival featuring sky diving, demonstrations by its air force and lots of beer to promote a newly renovated and upgraded commercial airport in the coastal city of Wonsan that it hopes will draw for foreign tourists. (Photo by Wong Maye-E/AP Photo)

North Korean soldiers participate in a mass military parade at Kim Il-Sung square in Pyongyang on October 10, 2015. North Korea was marking the 70th anniversary of its ruling Workers' Party. (Photo by Ed Jones/AFP Photo)

In this picture taken on January 5, 2022, people take part in a demonstration march after the Pyongyang City rally to carry out the decision of the 4th Plenary Meeting of the 8th Central Committee of the Workers' Party of Korea, at Kim Il Sung Square in Pyongyang. (Photo by Kim Won Jin/AFP Photo)

This picture taken on April 25, 2022 and released from North Korea's official Korean Central News Agency (KCNA) on April 26 shows a military parade to celebrate the 90th anniversary of the founding of the Korean People's Revolutionary Army at Kim Il Sung Square in Pyongyang. (Photo by KCNA via KNS/AFP Photo)

A fireworks display decorates the night sky to celebrate the New Year, as crowds of people look on, at Kim Il Sung Square in Pyongyang, North Korea, early Friday, January 1, 2021. (Photo by Jon Chol Jin/AP Photo)