The man was to be taken to the Lockhart River township for medical assessment after he was found about 3pm on Thursday, close to the to the camping ground where he was reported missing.

Helicopters were called in to help search for the man when he left his Cape York Peninsula campsite, about 20 kilometres from the Lockhart River, about 11am on Wednesday and had not returned by 5pm.

It was understood the man had been staying in one of the Cooks Hut camping area's six sites, where some of his belongings were found.

The Lockhart River region is a known crocodile area but Griffith University apex predators expert Professor Hamish McCallum said incidents were rare unless people weren't aware of the animal's habitat.

He said there was a large population in Queensland's north, especially with breeding season just beginning.

"Saltwater crocodiles are there because of food supply and there are suitable places for them to reproduce," he said.

"They start to breed in the west ... females do protect their nests and males can be quite territorial."

Professor McCallum said the biggest crocodiles caught in the north were between four to five metres.

"Large crocodiles of over three metres tend to eat large mammals and the bigger ones can take something to eat as big as cattle," he said, adding that the reptiles were difficult to spot in the water.

"They can be easy to mistake with a log but if you were to see one, you would just see maybe the eyes and just the tip of its snout in the waterline but they can be quite explosively out of the water.

"They certainly can launch their body length (out of the water) very, very quickly."

Police and a rescue helicopter continued their search on Thursday.