Deep below the foundations of Fremantle Prison more than 125 years ago, criminals toiled to excavate more than 1km of tunnels by hand.
It was backbreaking work, but the tunnels were critical for the supply of water to a new colony.
And they used round metal boats known as coracles to carry their tools and materials.
From next week, a complex operation will begin to painstakingly remove two coracles from muddy earth where they were abandoned more than a century ago.
"As far as we know, these are the only coracles ever used in WA," prison curator Olimpia Cullity said. "That makes them unique items and worth saving.
"These objects are 125 years old and slowly corroding away. Their removal will be technically difficult as they are large and fragile, semi-submerged in water and mud and deep underground."
Traditionally made of wood and animal hide, coracles were popular in west England, Scotland and Wales where they were used for fishing for centuries.
Ms Cullity said prison and WA Museum staff would begin extracting the coracles on Monday.
They would be treated to halt deterioration and later put on display at the jail. The prison tunnels opened for public tours by foot and boat in 2005.