Police are currently searching for a 20-year-old man last seen in the Gympie area overnight.
Initial information suggests he was swimming in waist deep water with a group in the Mary River at the corner of Traveston Crossing Road and Dobson Road at Kybong just after midnight.
The group were using headlights to light the water near their campground where they were wading.
They saw the man, turned around and then noticed he had disappeared.
Three Queensland Fire and Emergency Service swift water rescue crews assisted to try and locate the man without any luck.
Police are continuing their search today, assisted by divers and State Emergency Service personnel who are scouring the area.
He is described as Caucasian with olive skin, is of a medium build, has dark hair and was last seen wearing dark coloured shorts and a short-sleeved shirt.
Investigators are particularly urging any local property owners to keep an eye out for the man.
Anyone in the area who may have seen him or have further information is also urged to contact them.
If you have information for police, contact Policelink by providing information using the online suspicious activity form 24hrs per day at www.police.qld.gov.au/reporting or call 131 444.
You can report information about crime anonymously to Crime Stoppers, a registered charity and community volunteer organisation, via crimestoppersqld.com.au 24hrs per day or call 1800 333 000.