"The cork in the bottle had actually popped into the bottle. If there had been another big tide, it would've filled up with water and that would've been the end of the note. It was just lucky that we found it."
The couple returned to their home in Houhora, north of Kaitaia, and carefully retrieved the piece of paper using bits of wire.
What they found was a note written on special stamped-stationery marked "P&O" complete with a picture of the ship the note is thought to have come from - the SS Strathnaver.
The hand-written note, dated March 17, 1936, reads: "At sea. Would the finder of this bottle kindly forward this note, where found, date, to undermentioned address."
It is signed H.E Hillbrick, 72 Richmond Street, Leederville, Western Australia.
Yesterday Mr Flood managed to track down a distant member of Herbert Ernest Hillbrick's family who was "very excited" about their discovery. Mr Flood also managed to find a picture of Mr Hillbrick.
The Strathnaver ocean liner, operated by the Peninsular and Oriental Steam Navigation Company, was launched in 1931.
It was the sister ship of the RMS Strathaird - the pair were known as the "White Sisters" and both served the Australian mail route and travelled on the Sydney run in the mid 1930s.
The bottle is the third find of its kind for Mr Flood, who found a message in a bottle from a man in Australia and another, also from across the Tasman, from two 14-year-old girls.
He said he hadn't replied to that one yet, instead leaning on his son, who he said was a similar age, to do so.
Mr Flood said in both those cases the bottles had been in the water for only about a year.
"To find one so old is insane. It's quite exciting," he said.
"If it could talk, how many islands has it been to?
"It could easily have been two or three times around the world."
