Ms Cremer, 31, was last seen in June 2023 and is believed to have disappeared during a bushwalk at Philosopher Falls, in Tasmania's rugged northwest.
Five bones, teeth and a Honda car key were found by Tasmania Police after a two-day search of the Arthur River area on Sunday and Monday.
The operation focused on a 350-metre stretch of the river, about 2km from Philosopher Falls, near Cradle Mountain.
Severe weather forced the search team, which consisted of police and wilderness paramedics, to camp out overnight on Sunday.
While the remains have been sent for forensic testing, police have confirmed the car keys belonged to Ms Cremer.
"We still have Celine's car within our possession, so we tried the key and it worked," Commander Nathan Johnston told reporters on Wednesday.
He said the discovery was "another" indication investigations were moving in the right direction and is consistent with the theory Ms Cremer became lost during a bushwalk.
Police are awaiting the outcome of a review of the most recent search effort to determine any future operations.
"A big part for us is to try and find as much as we can, if it is Celine, to reunite as many items as we can with her family," he said.
Cmdr Johnston said police have been in constant contact with Ms Cremer's family, adding the latest findings would confirm their likely belief their daughter had died.
"It's another piece in the puzzle," he said.
"It hasn't come as a great surprise, but I guess it's still a big shock."
It follows another breakthrough in late January when officers found human remains and items of clothing she was believed to have been carrying.
Forensic testing is ongoing to determine whether the remains belonged to Ms Cremer.
The Belgian was reported missing by her family in June 2023, sparking a major search involving police and SES ground crews, specialist swift water rescue personnel, drones and a helicopter.
The recent breakthroughs were made in an area of dense bushland that police only surveyed by helicopter in earlier searches.
"This area hadn't been done by detailed search at the time and that was based on the theories and the expertise that we had been provided," Cmdr Johnston said.
Ms Cremer was believed to have set off on a walk and her car was found in the Philosopher Falls car park a day after the missing person's report was filed.
Clothing, including a polar fleece jacket, thermal top and bra, were found in January's search after a bushwalking group discovered her phone in December.
Forensic testing of the remains continues and responsibility for the investigation into her disappearance will fall to the state coroner.
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