Onlookers have posted videos and photos of an animal's snout breaking the surface of Moreton Bay near One Mile Jetty near Dunwich on North Stradbroke Island, also known as Minjerribah, on Friday morning.
Queensland rangers have been searching for a marine reptile after a local kayak tour guide reported a three-metre crocodile at Myora Springs, about 4km from the jetty, on Wednesday.
Local Pam Bazza posted three photos of the animal's snout with the caption "The Dunwich crocodile!!!" and concerned face emojis with another user asking if it was really a crocodile.
"Yes! Definitely a crocodile!!!" Ms Bazza replied on Facebook.
Another person said she should report the animal to authorities, but she replied: "Parks and Wildlife, Rangers, Police …. and now politicians are here!"
A video of the same incident was later aired by Nine News.
The Department of Environment and Science is yet to confirm the presence of a wayward apex predator in southern Moreton Bay.
If a crocodile is found it will be in what's classified as an atypical habitat zone and removed from the wild under the state government's management plan.
Quandamooka man Mark Jones first reported the crocodile after seeing it while leading a kayak tour on Wednesday morning and other holidaymakers had also seen the creature in recent days.
Saltwater crocodiles aren't known to venture so far south in Queensland, with Minjerribah about 440km south of their habitat range in Hervey Bay.
The last verified crocodile to venture into the southeast was a 3.83m animal, which was shot dead by locals at Logan Village on the Logan River in 1905.
There have been earlier crocodile sightings further south as Nerang, Lismore and Angourie, but only the Lismore reptile has been verified and it was an escaped pet.
Experts speculated the crocodile on Minjerribah could have been released by a private owner, although that's highly unlikely, or it could have drifted from the most southerly known range of the marine predators in Hervey Bay.
Crocodiles can travel large distances at sea, particularly after floods, and ocean temperatures have topped 26C in recent days in southeast Queensland.
There were 41 crocodile attacks on humans, 12 of them fatal, in Queensland between 1985 and 2021.
19°C