A four-year-old girl's message in a bottle would have "needed help" to get from Lancashire to Western Australia in six months, an expert has said.
Alesha Johnson got a reply to her message from Australia
Alesha Johnson threw the bottle into the water at Morecambe Bay last July, enclosing her picture and Heysham address as part of a nursery project.
She received a letter from a 10-year-old from Perth, who said he had found the bottle in a local boatyard.
But oceanographer Peter Challenor said it could not have travelled unaided.
"I think it is extremely unlikely," said Mr Challenor, of the National Oceanography Centre, in Southampton.
He said the world's currents would have prevented the bottle getting to Australia.
"It has probably got a lift caught up in a ship and released somehow," said Mr Challenor.
"It could have got into the bilge but even then most ships have filters."
Alesha's note read: "If you get this message, please write back."
The Australian boy, who said only that his name was Bob, wrote backing saying he had asked his father to look up Heysham on the internet.
The child did not enclose an address as he said he was moving house, but would write back when he had his new address.