Police have asked anyone at the Howard Smith Wharves, including people in surrounding businesses and on the riverside walkaway, to stay away from the area.
A police helicopter has flown over the area with sirens on, with a warning for residents to “move away from the water’s edge”.
Officers are also walking around the wharves on foot, asking people to keep clear of the area.
Some residents stood on nearby balconies to have a look at the pontoon.
“Locals are advised to avoid the area and unless absolutely necessary, stay home,” Queensland Police said.
Brisbane City Council is on standby with drones, in order for council workers to assess the situation.
However, council workers will have to wait until the police helicopter lands.