As dawn breaks over a Johannesburg park, some 300 people dance in silence, some dressed as Batman, Spiderman or Wonder Woman.
Others are in tutus, black catsuits or animal "onesies". Many have masks and painted faces.
This is "Secret Sunrise" - a new urban craze in which people gather outdoors in the early morning to express themselves to a soundtrack played through headphones.
Later in the day, they will toil at office desks in South Africa's economic capital, or be students attending lectures, but for a short time they proudly embrace a less reserved way to live.
"The point is to get people working towards something that makes the daily grind a little bit less boring," said Cheryl Hudson, who has a job in project finance when she changes out of her purple dance outfit.
"We have it in the week to try to transform the day because after an experience like this, you connect with people.
"You get to be a different version of yourself, you go forth, and you are not grumpy when you get into the office.
"As adults, we sometimes forget... that we really need to play.”
On Wednesday morning, sleepy participants congregated at 6:00 am in the park in the northern suburbs of the city under a dress theme of "superheroes".
"It is an opportunity to go wild, to be ridiculous," said Jamie Beron, a yoga teacher dressed in leopard-print leggings, fishnet gloves and a very tight silver shirt.
"It is a sober, morning dance party... with a little bit of imagination, a whole bunch of crazy people and, most importantly, a lot of fun."
Beron, 31, is one of the organisers of the fortnightly event, which follows similar dawn dances in London, Los Angeles, Tokyo and other cities around the world.
"I'd like to invite you to an adventure," Beron told the crowd as they yawned, stretched and slowly came to life.
"We are going to another world. It is an opportunity to go back to when you were a child, when you could fly, when you were a superhero."
With a rainbow in the sky and against a background of distant skyscrapers, the group soon bursts into energetic moves.
During the hour-long session, they crawl on the ground, form conga lines and run in circles.
Two women with their faces hidden behind golden masks jump around together, while a barefoot man with a cape made from a blanket bounces up and down on the spot.
The venue of each "Secret Sunrise" is revealed only the day before to build suspense, and tickets costs 100 rand ($6.30).
The last event in Johannesburg was held on a roof terrace and was a '70s theme that became a tribute to the late David Bowie.
At the end, all the dancers hold hands and form a large circle before dispersing.
A sweaty Captain America - better known during work hours as Travis Kruger, a 31-year-old used-car salesman - contrasted the experience to a nightclub or rave.
"That is alcohol and smoking. It is healthy here. There is no aggressiveness," he said.
"With your earphones, you pretty much block out everything.
"You can dance where no one cares if you can dance. Everyone is just happy and free and you get to hug people.
"You don't have to say any word to anyone.
"I have to go to work after this. Last time I did this, I had the most amazing day at work, so it is just a good start to the day."