Pirate is a main item used to getting Treasure Map. Having a pirate grants a chance to get a map every tick (= 1 second). It can be purchased in Game Shop at 25,000,000 coins for the first one, up to 10 pirates.
Green Treasure Map Edit
After receiving the Runite Spyglass as a reward from the Pirate's Treasure quest, the pirates start looking for Green Treasure Map, in additional to normal Treasure Map. The green version leads to Green Treasure Chest, which give better loot and far better chance to get Green Orbs than the normal chest.
Pirates cost efficiency Edit
Each pirate later increases the chance of getting a map with no linear drop rate, while the price is incrementally increased, thus diminishing returns occur. The chance of getting a map is only unofficially confirmed and rather based on Diamond Hunt 1 data.
With one pirate, players get a map on average roughly every 4 days. This lowers to 2.3 days at 10th pirate. Generally, buying the first pirate usually is enough to start with.