Fun turns to tragedy for NSW boy

Ryan Teasdale was mucking about with friends, sliding down park hill on a bodyboard, when he was sucked into a stormwater drain on the NSW south coast.

The body of an 11-year-old who was sucked into a storm water drain in NSW has been recovered. (AAP)

For years whenever it's really rained kids have slid down a muddy hillside park in Unanderra on their bodyboards.

But this week the fun turned to tragedy when 11-year-old Ryan Teasdale died after being sucked into a stormwater drain when mucking about with his older brother and a dozen mates.

Ryan went missing at Riley Park on Thursday afternoon as torrential rain swept through NSW's Illawarra region.

His 13-year-old brother raised the alarm about 4.30pm when he couldn't find his sibling, sparking a frantic search which carried on until after midnight.

More than 100 people including SES, NSW Police and council, marine rescue and ambulance personnel resumed the search at first light on Friday.

Social media posts from locals suggest the park has been a popular spot for youngsters to play on bodyboards for decades.

"We saw them, about 20 kids with their boogie boards, it's something kids do there all the time. So devastating," one woman wrote on Facebook.

Search crews lifted the covers off drains across the road from the park, where water was rushing, while a contractor used a camera to search parts of the drainage system that were not easily accessible.

Ryan's body was found after 11am on Friday in a creek bed at the end of a stormwater drain, about 500 metres from the park.

"The family asks that their privacy be respected," Superintendent Zoran Dzevlan told reporters on Friday.

He said the heavy rainfall and subsequent torrents of water rushing through the drains overnight were factors in the boy's death.

Wollongong's mayor, Gordon Bradbery, visited the Teasdale family on Friday morning. He told AAP "the city is behind them" as they grieve.

The stormwater drain located at the bottom of Riley Park - which measures about 60cm across - isn't covered by a grate and the mayor said the council won't be installing one.

"Covering it is not the solution as it could create other problems," he said.

The mayor argues that debris stuck against any grate could create a dam which would then flood nearby properties.

The key was to teach children not to play in floodwaters, he said.

Ryan's bodyboard was found away from the park - it seemingly hadn't been sucked into the drain.

The Illawarra region was drenched on Thursday which caused widespread flooding, inundating major roads including the Princes Highway, which was closed in both directions, and flooding schools and buildings.

Ryan was a student at Wollongong's Lindsay Park Public School.