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)

A man and his son ride a horse at Tahrir Square in Sanaa, Yemen on January 21, 2021. (Photo by Khaled Abdullah/Reuters)

Jason Bregartner and his son Jason Jr., 2, sit in costume with J.D. Mirable at a bustop during the NYC Zombie Crawl in New York, October 18, 2015. (Photo by Shannon Stapleton/Reuters)

English actress Liz Hurley, 55, poses topless in the snow in a photo taken by her son in United Kingdom at the end of January 2021. Brit stripped to white bikini bottoms from her own swimwear range and draped herself in a coat. (Photo by Instagram/The Sun)

A man washes his horse as a woman bathes her son at concrete water pens under a flyover in a slum area in Kolkata, India October 21, 2016. (Photo by Rupak De Chowdhuri/Reuters)

A woman carries her son in a bucket after collecting water from a municipal water tanker on the outskirts of Chennai, India, July 4, 2019. (Photo by P. Ravikumar/Reuters)

British actress and model Elizabeth Hurley (L) and English actress Pear Chiravara in “Strictly Confidential”, 2024, directed by Liz Hurley's son Damian Hurley. (Photo by Backgrid USA)

Actor and former California Governor Arnold Schwarzenegger (R) and his son Patrick Schwarzenegger (L) attend “Arnold Classic Europe” 2011 Party at “Jardines Cecilio Rodriguez” on October 7, 2011 in Madrid, Spain. (Photo by Carlos Alvarez/Getty Images)