"The SES and Port Stephens-Hunter police have rescued a 16-year-old boy who was trapped between debris in waist-deep water after falling into the river about 9am," NSW deputy state emergency operations controller Karen Webb said.

"The teen was in the water for almost two hours before specialist SES officers were able to free him and safely return him to the riverbank. He's since been taken to hospital with suspected broken ribs."

The teenager was trapped against timber in the river and had to be freed by an NSW SES Swiftwater Rescue technician.

He was hauled to safety by the combined rescue teams. All those involved are now safe.

Ms Webb said Brisbane Water police on the Central Coast and residents had "put their lives at risk to rescue five men whose fishing boat capsized as they tried to navigate in the dark to go fishing" on Saturday night.

"The water conditions were so dangerous that Marine Area Command were unable to assist, yet none of the men were wearing life jackets and struggled to swim," she said.

She was disappointed that she had to remind people to act responsibly and "not take risks in these types of conditions, especially when around floodwaters".

"We are investigating after a video surfaced online [on Saturday] of a man jet skiing in floodwaters on the Central Coast, which is behaviour so reckless I can barely comprehend it."