Treasure is normally seen as a collection of gold and silver, or even valuable gem stones such as diamonds, rubies and pearls hidden somewhere waiting to be discovered. However Treasure can refer to anything valuable from an old vase worth millions to a vow between friends or a memory of an experience. Sometimes what one person may consider to be a treasure, others may not, hence the phrase: "One person's trash is another man's treasure". Generally, a treasure is something that a person is not willing to give up without a fight.
In One Piece, the idea of treasure has been raised a number of times. While most pirates, like Buggy or Nami, value gold, silver and jewels, there are others who hold other treasures dearer to their heart, leading to many items being stated to be a "treasure". These items often gain their value for personnel reasons, but are also something people in the One Piece world themselves are willing to fight for.
Zoro considers his vow with Kuina to become the best Swordsman as a treasure and carries her sword with him always.
Nami considers money and her tangerines to be treasure. However her true treasure is the people of Cocoyashi, going as far as stealing a large amount of money to save their lives.
Usopp considered Going Merry to be a treasure, not only to himself, but the entire Straw Hat crew. When Luffy announced that they were getting a new ship because the Merry was damaged and beyond repair, Usopp became angry and got into a fight with him.
Sanji considers his hands to be his treasure, because as a cook, he would be unable to prepare meals if anything happened to them, hence his kick based fighting style.
Chopper's hat and flag are his treasures because Dr. Hiluluk gave them to him. He also considers human life and proper treatment to be a treasure of sorts. When Hogback struck Victoria Cindry, Chopper became angry and attacked, seeing Hogback, who used to be a doctor and was supposed to help people with their problems, disregard his vow for human life.
Robin considers history more valuable than gold and to her there is no bigger crime than destroying something from long ago such as a set of ruins. The reason being is that humans can study and look back at history, but they can never return to the past, thus when it is destroyed that part of history is forever lost.
Brook considers his afro a treasure because it's the only thing Laboon would recognize him by.
Gaimon considered the animals on his island a treasure after finding out that the treasure he was guarding for twenty years was already gone before he got there.
Crocodile considered Pluton a treasure as it was the key to his dreams of conquering the world.
To the Shandia their former home of Shandora was their treasure and they were prepared to die for just one bag of Vearth.
Ace, before exhaling his last breath, thanked his brother and his friends for loving him despite his heritage, suggesting that those relationships were more precious to him then any amount of gold, a trait he had in common with his captain Edward Newgate.
Sabo considers the bond he had with his brothers Ace and Luffy to be his greatest treasure.
Edward Newgate considered his pirate crew and allies as his treasure, so his treasure was family.
Donquixote Doflamingo has knowledge of the existence of a hidden National Treasure of the World Nobles which if exposed world could shake its foundations, and was so important that they complied with Doflamingo's blackmail granting him all the privileges of a Celestial Dragon. It is also said that if this treasure is used in combination with the Ope Ope no Mi, it would allow the person to effectively conquer the entire world.
A map is a diagram or graph designed to show the locations of things as they lay on the landscape, such as where forests or villages are located. They are normally used as a guide to get from one location to another with or without the aid of a compass. In the world of One Piece, they normally take the form of a treasure map or island map.
Despite their association and love for plunder and treasure, most pirates in reality were broke and had little treasure at all because they spent most of what they stole on alcohol, women, and gambling.