Swimmers brandishing short, curved sticks held their breath as they somersaulted and dove towards a weighted puck at the bottom of a Hong Kong swimming pool, vying for first place in a sport likened to voluntary drowning.
The annual underwater hockey tournament, ominously advertised as "physical hell", nevertheless drew a roster of hardcore enthusiasts from countries across Asia to the Chinese city over the weekend.
"You have to choose when to use your breath and when not to... Anyone that's got the puck, you know that they've got some level of suffering," Leo Lines, a Japanese-New Zealander competitor from Hokkaido, told AFP.
"I love that."
Suited up in snorkel masks and fins, players only resurface for air when they absolutely have to, and their heads remain constantly underwater so they can monitor the game.
There are six players on each team and no goalkeepers, while referees watch for fouls and send players to a penalty box for serious rule-breaching.
"You're so into trying to succeed, trying to score the goal, that you forget about breath hold and how tough it is," competitor Rita Frieske, a Hong Kong-based Polish academic, told AFP.
Games last 30 minutes and are split into two halves with a three-minute break in between.
The gruelling sport has created a tight-knit community.
"It's like that sadistic study that forces everybody to survive together and then you stick together for a long time," Malaysian player Hui Chin Teoh said.
Underwater hockey, previously known as "octopush", was invented in England in 1954 as a way to keep divers fit during the off-season winter months.
While not yet an Olympic sport, it is recognised by the International Olympic Committee, and made its debut at the Southeast Asian Games in 2019.
Competition organisers hope that as underwater camera technology improves, the spectator experience will too.
"The future of underwater hockey, thanks to social media, is more active now than before," said head coach and tournament director Nowie Ignacio.
"When I was playing, it was just word of mouth. Now there are a lot of avenues to see it... (competitions) are actually televised live now," he said.
Many players at the Hong Kong tournament have their sights set on the Elite world championship in France next April, which organisers expect will draw around 20 nations.
"People are starting to understand what underwater hockey is," Ignacio said.
"The dream is the Olympics."
fbw/dhw/mjw