A dozen South Africans dressed as mermaids and mermen frolic in a Johannesburg pool, mimicking the movement of the mystical sea creatures.

Mermaiding is a fast-growing sport worldwide, and now South Africa has its own school to teach it -- the "Merschool".

Before diving in, students each slip on a brightly coloured fabric tail ending in a monofin.

The swimmers are black and white, from 13 years old to in their forties. They include a schoolteacher, a yoga instructor and even an accountant.

"It's lots of fun," says mermaiding instructor Izelle Nair.

"It's for fitness, it's for fun, it's for fantasy, it's therapy -- but most of all, mermaiding is a sport."

To be a mermaid -- or merman -- all that is required is a little technique, some breath-holding skills and a love of costumes. Photo: AFP

In the water, students undulate up and down the pool perfecting their dolphin kicks, or practise sculling -- hand movements to propel the body also used in synchronised swimming.

"We swim with a dolphin technique and we use sculling, and then we put it all together and we work out a little sequence," Nair says.

To be a mermaid -- or merman -- all that is required is a little technique, some breath-holding skills and a love of costumes.

Underwater, students attempt to perform a graceful aquatic backflip.

Students practise tail flips at the 'Merschool.' Photo: AFP

Nadia Walker, another mermaid coach from the world of synchronised swimming, says both sports have much in common.

"The back rolls, some of the warm-ups and activities that we do, come from swimming," she says.

The school hopes to send at least one contender to next year's World Mermaid Championships in China -- and that one day the discipline will become an Olympic sport.