Bon Chari are vehicles that are used to travel around the Sabaody Archipelago. They are affixed inside the bubbles, where the user has to pedal in order for the propel to spin and provide motion to the vehicle. They do not, however, work outside of the archipelago. The reason for this is that there is no atmosphere like it except for Fish-Man Island.
The Bon Chari shop salesman at Sabaody Archipelago lends a person a Bon Chari for 500 or sells them for 10,000. For travelling visitors, it is wise to rent a Bon Chari, because if they were to buy one and take it with them on their travels, the vehicle will not work beyond the Sabaody Archipelago.