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)

Hot air balloons in flight over Melbourne, Australia on January 24, 2022. (Photo by Rex Features/Shutterstock)

Japanese Macaque monkeys soak in the warmth of mountain hotsprings at Jigokudani Monkey Park, in Yamanouchi, central Japan, 19 January 2014. The Japanese Macaques (Macaca fuscata), also referred to as Snow Monkeys, live freely in this area that is covered by snow one third of the year. Jigokudani is the only known place in the world where monkeys bathe in natural hot springs. As a habit, they come down from the mountains where they spend the night and bath during the day. (Photo by Kimimasa Mayama/EPA)

A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

Last weekend, the National Building Museum in Washington, D.C., opened a 10,000 square-foot ball pit to the general public, and everyone cheered that, finally, someone made their childhood dreams come true.

A female Kurdistan Workers Party (PKK) fighter works on her laptop while watching a Kurdish TV station at a base in the Sinjar mountains, March 11, 2015. Women fighters at a Kurdistan Workers Party (PKK) base on Mount Sinjar in northwest Iraq, just like their male counterparts, have to be ready for action at any time. Smoke from the front line, marking their battle against Islamic State, which launched an assault on northern Iraq last summer, is visible from the base. Many of the women have cut links with their families back home; the fighters come from all corners of the Kurdish region. (Photo by Asmaa Waguih/Reuters)

Redhead Day (Roodharigendag in Dutch) is the name of a Dutch summer festival that takes place each first weekend of September in the city of Breda, in the Netherlands. The two-day festival is a gathering of people with natural red hair, but is also focused on art related to the colour red. Activities during the festival are lectures, workshops and demonstrations which are aimed specifically at red-haired people. The festival attracts attendance from 50 countries and is free due to sponsorship of the local government.