Deep dive into the world of underwater hockey

In underwater hockey, players scramble for a heavy puck and move it along the bottom of the pool. Caleb Ming for ESPN

SINGAPORE -- Underwater hockey? It's a sport that prompts many questions when players try to explain it to those who have never seen the game. Fans are familiar with the ice and field versions, but now imagine it under 13 feet of water. The Singapore national team offered ESPN an under-the-waves look at this unique sport, which debuted at the Southeast Asian Games this week in the Philippines.

How is it played?

Typically played with six players on each team. Opponents dash for a weighted puck and move it along the bottom of the pool toward an open-ended goal that is 3 meters (about 9 feet) wide.

There are no goalies -- each side uses teamwork and formations to defend and score. It is a no-contact sport, in which pulling and grabbing are not allowed.

Two referees watch for fouls and goals, and players can be relegated to a penalty box. The playing field is a pool that is 25 by 15 meters (27 yards by 16.5 yards) with a depth of 2-4 meters (6-13 feet).

The puck weighs 1.5 kilograms (about 3 pounds) and is made of lead alloy coated with plastic.

Players wear large fins and a snorkel mask while carrying a small stick (the pusher stick) in a thickly gloved hand. The pusher stick dimensions have to fit within a 300 by 100 millimeter box (about 11 inches by 4 inches).

Each game has two 15-minute halves with a short halftime. The teams begin the match on either end of the pool, with the opening buzzer signaling a mad dive as the players scramble for possession of the puck placed in the middle at the bottom.

Obviously strong swimmers are favored, but the ability to hold one's breath for long periods of time and stay underwater is equally important.

How did it start?

Originally known as "octopush," the game was invented in Great Britain in 1954 to help train divers and British commandos. The sport is recognized by the International Olympic Committee and is governed by the World Underwater Federation (CMAS).

It is now played in more than 40 countries, with an estimated 15,000 participants. New Zealand, Great Britain, France, Turkey, Australia, South Africa and Colombia are the leading underwater hockey nations. Last year's world championships in Quebec drew 17 nations, with powerhouse New Zealand sweeping both the men's and women's elite divisions.

International play

Underwater hockey made its debut in a multisport, international competition this week in the Philippines at the Southeast Asian Games -- a regional, smaller version of the Olympics. Singapore, the Philippines, Indonesia and Malaysia all fielded teams.

The SEA Games host gets to pick new sports outside of those usually contested in the Olympic Games to showcase strengths. For the 2019 SEA Games, which officially opened Saturday, the Philippines picked underwater hockey to be showcased, with the strong backing of its regional counterparts.

Tristan Reynard, the world tournament director for CMAS, said the local countries led the charge for underwater hockey's inclusion in the SEA Games.

"The Southeast Asian federations are really passionate about the sport and the SEA Games inclusion is due to them working together to make it happen. In the last 15 years, the sport has developed in Asia," Reynard said. "The [competing] countries are all developing and it's a great opportunity to develop their skills, as the teams are fairly equal in ability."