Messages in a bottle written by two Australian soldiers in 1916 have been found more than a century later on the country’s south-western coast.

The cheerful notes were penned just a few days into their voyage to join the battlefields of France during World War One.

One of the soldiers, Pte Malcolm Neville, told his mother that the food on board was “real good” and that they were “as happy as Larry”. Months later, he was killed in action at the age of 28. The other soldier, 37-year-old Pte William Harley, survived the war and returned home.

The letters have been passed on to their descendants, who have been stunned by the discovery.

The bottle was found earlier this month on the remote Wharton Beach, near Esperance in Western Australia, by local resident Deb Brown and her family.

She was visiting the beach with her husband and daughter on one of their regular quad bike trips to clear up litter, when they spotted a thick glass bottle in the sand, she said on Tuesday.

“We do a lot of cleaning up on our beaches and so would never go past a piece of rubbish. So this little bottle was lying there waiting to be picked up,” Ms Brown told the Associated Press news agency.

Though the paper was wet, both letters were still legible, so Ms Brown began tracking down the soldiers’ families in order to pass them on.

Ms Brown located Pte Neville’s great-nephew, Herbie Neville, by searching for the soldier’s name and the town he was from online, as his mother’s address was included in the note.

Mr Neville told ABC News the experience had been “unbelievable” for his family, especially for Marian Davies – Pte Neville’s niece – who remembers her uncle leaving to go to war and never returning.

The second letter, written by Pte William Harley, was addressed simply to whoever found the bottle. His mother had died years earlier.

Pte Harley’s granddaughter, Ann Turner, told ABC she and the soldier’s four other surviving grandchildren were “absolutely stunned” by the message.

“It really does feel like a miracle and we do very much feel like our grandfather has reached out for us from the grave,” she said.

“I feel very emotional when I see that the other young man had a mother to write to, and that message in the bottle was to his mother, whereas our grandfather long ago had lost his mother so he just writes it to the finder of the bottle.”

The bottle was thrown overboard “somewhere in the Bight”, Pte Harley’s letter said, referring to the Great Australian Bight off the country’s southern coast.

An oceanography professor told ABC it may only have been in the water for a few weeks before it landed at Wharton Beach, where it may have remained buried for 100 years.