Couples take part in the “Love and Challenge Marathon” in Hanoi, Vietnam, 16 August 2015. Fifty couples, who are going to get married, participated in the event which is held the fifth time. This year, the winners of the marathon received a honeymoon trip to Malaysia. (Photo by Luong Thai Linh/EPA)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

Two hippopotamus are fed with pumpkins at the Hanoi Zoo, in Hanoi, Vietnam, 25 October 2018. The zoo has been the home for more than 800 animals of over 90 different species, including three hippopotamus, since it was built in 1976. (Photo by Luong Thai Linh/EPA/EFE)

A Vietnamese cosplayer poses as police officer character from the game during the League of Legends (LOL) Mid-Season Invitational 2019 play-in group stage, in GG Stadium, Ho Chi Minh, Vietnam May 5, 2019. (Photo by Reuters/Kham)

A Vietnamese woman, wearing the traditional “ao dai” long dress, poses for photos along peach blossom flowers ahead of the Vietnamese “Tet” (Lunar New Year festival), in a field in Hanoi, Vietnam, February 2, 2016. (Photo by Reuters/Kham)

Picture dated May 1st 2022 shows Cambridge University students enjoying the Caesarian Sunday party on Jesus Green in Cambridge, United Kingdom. Thousands of Cambridge University students descended on a city centre park yesterday (Sun) as their annual summer party took place officially for the first time in three years. (Photo by Bav Media)

Student of Meiji University Yuki Hou licks a screen of Taste the TV (TTTV), a prototype lickable TV screen that can imitate the flavours of various foods, during its demonstration at the university in Tokyo, Japan, December 22, 2021. (Photo by Kim Kyung-Hoon/Reuters)

A Christian evangelist hands out cards reading “God is Good!” as fans arrive for the University of Georgia football game against the University of Tennessee, ahead of the midterm elections including former Georgia football star and Republican U.S. Senate candidate Herschel Walker, in Athens, Georgia, U.S. November 5, 2022. (Photo by Jonathan Ernst/Reuters)