Requirements: You need 60 coins or another way to and from Karamja.
Asking for treasure-
To start Pirate’s treasure speak to Redbeard Frank in Port Sarim. You can find him by the pub on the eastern edge of Sarim. Tell him you are in search of treasure and he says he might tell you of some if you bring him some Karamja Rum. He will warn you that you will have to slip it past the Customs office. Head south west along the dock until you come to 3 sailors in blue clothes. Right click on them and select pay-fair to travel to Karamja, the trip will cost 30gp. Climb off the ship and head west until you come to a bar, it should be the second building you pass. Trade with Zambo and buy a Karamja rum for 30gp.
Getting a job-
Now you have to get it off the island, this won’t be as easy as it seems. Trying any of the obvious methods such as just leaving, teleporting, or banking will destroy the rum. Head to the building east of the bar and speak to Luthas. Ask him for employment and he will tell you that he needs a crate of bananas filled.
Banana Collector-
Gather 10 bananas from the trees west of his house and then head back, by the south east corner of his house is a crate. Select the fill option and all the bananas will be put inside. Then use the Karamja rum on the crate to hide it inside. Speak to Luthas again and he will give you 30gp.
Another Job!?!-
Now go back to the boat and pay a customs officer to take you back to the island, you will have to let them search through your items. Head to the fish store to the north west and grab a white apron off the back wall. If there isn’t one there it should re-spawn shortly. Once you have your apron head to the building south of the fish shop and ask Wydin for a job. Wear your apron and head into the back room. Search the crate with a banana on top and you will find the rum.
What a great treasure chest-
Now head back to Redbeard Frank and talk to him. He will take the rum and give you a key, it is to his old captains room at the Blue Moon Inn. Head to Varrock and go to the Inn near the southern entrance. Go upstairs and use the key on the chest in the south-western room. You will find a message that tells you to go to Falador and find an X.
Fight to the death-
Head to Falador and go to the realtors house east of the furnace. A spade spawns on the ground in there, grab it. Now go to the garden north east of there. Next to the statue of Saradomin will be a large patch of dirt in an X shape. Dig with the spade and a level 4 gardener will attack, defeat him and dig again to complete the quest!