After an extensive search at Karana Downs near Mount Crosby, officers found the body about one nautical mile from where Mr Reddich disappeared on Sunday.

The body was found about 11am and a report will now be prepared for the coroner.

Police and SES crews scoured several kilometres during the search for the missing man, using sonar technology and dive teams.

Mr Reddich was with a group of friends when he dived into the water to fetch a ball, but did not resurface.

Tributes have started to flow for the young bodybuilder who competed in his most recent show a month ago, after making his debut in 2013.

National Amateur Body Builders Association Queensland president Mark Ryan described him as a "great kid".

"It will definitely affect a lot of people because a lot of people knew him and loved him." Mr Ryan said.

"He was a really dedicated, hard-working kid and it's a great tragedy.

"It's a very dedicated lifestyle. Your food has got to be very controlled and the training regime is very intensive. Not all of them have got the discipline like he had."

Mr Ryan said the association was planning a tribute to Mr Reddich at its next show.

On social media others paid their respects to Mr Reddich.

"Horrible things always happen to the best of us...You were such an inspiration to others and genuinely good bloke to be around," Michael Rowe wrote.

"You will be missed Ben! RIP bro," posted another friend, Aaron Visona.

On Monday, Inspector Charysse Pond said the search area was difficult to examine because of trees, rocks and boulders under the surface.

While the area is frequented by bull sharks, police said there was no evidence to suggest Mr Reddich had been attacked.