Improved concentration

Chan's diving therapy sessions began several years ago, when he had taught his sons, both of whom have autism, to scuba dive.

"It was magical. They could concentrate better underwater and they listened to me more," Chan said, speaking ahead of World Autism Awareness Day, which falls on April 2 every year. "Maybe because of the quietness and weightlessness underwater, they felt comfortable."

His friend, Winston Shum Chakwing, also noticed a change in Chan's sons after they became involved in the diving classes.

He suggested that Chan establish a nonprofit organization to teach diving to a larger number of children with autism, so that's what Chan did.

"I know how hard it is for autistic children to learn new things. It's almost impossible for them to take any interest in classes with ordinary children. I thought it (the nonprofit) was worth trying," he said.

Chan contacted a teacher in the special education department at Guangzhou Children's Palace, where youngsters can take part in extracurricular activities, and asked if young people with autism at the center would be interested in learning to dive.

The teacher asked around, and to Chan's surprise, many parents were eager for their children to learn.

Liao Chaoqing was one of them. Her son Yonghao, who was 19 at the time, has moderate autism. He had just graduated from a vocational high school, but he could lose control at any time, hitting his mother, shouting and throwing things.

"Maybe he was angry at me for not spending enough time with him when he was little. Maybe he thought I could be a target for his unconditional outbursts. When he got mad, he always came at me," Liao said.

Initially, she took Yonghao to a doctor, who prescribed medicine to help him control his temper.

"I was so anxious and on the verge of a breakdown," Liao recalled.

She added that no doctor or social worker was actively following Yong-hao's case, so there was no one she could turn to for help.