"Police are confident of the identities of the deceased but no information in relation to the pair will be released until formal identification has been completed and next of kin informed," a police statement said.
The car has been taken away to be examined and the serious crash investigation is continuing.
The crash happened at about 4.30pm on Tuesday.
Eyewitnesses later told police of concerns over the motorist's driving.
Eco Rafting Adventures owner operator Josh James Marcotte was one of the first on the scene.
He criticised police for not letting him enter the water and try and free them from the car despite being a certified swift water rescue technician.
But police said that since Mr Marcotte arrived "thirty minutes" after the crash, there were unlikely to be airpockets in the submerged vehicle, as windows were most likely smashed when it went through the barrier and into the river.
"We are not going to risk life and limb," West Coast area commander Inspector John Canning said.
