Police said no one saw the boy going into the water but have confirmed he was involved in a boating mishap at the popular camping spot.
It's been reported clothes belonging to the boy were also found near the river not long after he went missing.
Deep River at the falls is running fast and high after heavy rains, and the surrounding terrain is dense bushland, making the search particularly challenging.
Inspector Glenn Spencer told reporters crews were battling tough conditions and poor visibility.
"The water is very high flowing and there's lots of obstructions, very turbulent water and lots of rocks, lots of logs and very low visibility, within 30cm so it is hands and knees searching," he said.
Local police, divers, State Emergency Service volunteers, and police drones have been involved in the search but the ground search was suspended late on Tuesday.
Police are hopeful that water levels may fall overnight to help make searching easier and they remain determined to find the boy. Photo / 9 News
"They've maximised every opportunity we have to find the boy on land," Inspector Spencer said.
He said the boy's family were in the "grieving process".
The family remain in the area as the search continues.
