Sean Cole, of Darwin, and another man had gone swimming at the Mary River Wilderness Retreat despite warnings from resort staff to stay out of the water, The Sydney Morning Herald reported Sunday.
The crocodile grabbed Cole after he entered the muddy river about 4 p.m. Saturday and pulled him underwater. Police recovered the man's body early Sunday morning in the same area.
Cole was celebrating a friend's 30th birthday at the retreat in the Northern Territory, about 60 miles east of Darwin.
'When you get here, you are told there are crocs, that the river is full of them," said resort manager Erin Bayard. "Don't swim. Stay at least five meters (16 feet) back from the river. If people follow that advice, it is entirely safe. We have never had an attack before this.''
Senior Sgt. Geoff Bahnert of the Darwin police said the river "has the highest density of saltwater crocodiles in the world."