The Pirate Treasure is a chest full of very old and valuable treasure, which is made up of gold coins, chains, necklaces, jewels and chalices. The treasure was stolen from merchants by Captain Calles back in the 16th Century, and the chest was buried near Arlesburgh when he was hiding from the Merchants and the Navy. The treasure is now on display at the Sodor Museum.
During the 16th Century, Captain Calles used to sail the seas in his pirate ship, plundering the ships of merchants and stealing their goods. Eventually, the Merchants and the Navy teamed up, and together they began tracking Calles down. In order to escape, Captain Calles hid his ship in a cavern near Arlesburgh. He buried his treasure above the cavern and drew a map so that the treasure could be found again later on, but he never came back to retrieve it.
During the construction of the Harwick Branch Line, Marion discovered the treasure chest when she was digging into the cliffside, but was not aware of what she had found. She found out what she had discovered the next morning, when she accidentally dumped the treasure chest onto Thomas, spilling the treasure all over him. Marion was praised by the Fat Controller, who decided to donate the treasure to the museum.
In order to keep the treasure safe until it could be given to the museum, the Fat Controller locked the treasure chest in a safe in his office at Knapford. However, the safe was destroyed by Sailor John, who used a stick of dynamite to blast his way into the safe and office. Though Sailor John nearly managed to escape, he lost the treasure chest when Skiff capsized, after he was too stubborn to throw the heavy chest overboard. The treasure chest sank to the bottom of the sea, and Sailor John gave up. The chest was later recovered by a group of scuba divers, and it was placed on display in the museum. (TVS; Sodor's Legend of the Lost Treasure)