Going Merry is the name of the first ship the Straw Hat Pirates use in the manga and anime One Piece. A victim of an unexplained name change, the Merry is, for some reason, called Merry-Go in the English dub.
Given to crew captain Luffy by Usopp's childhood friend Kaya in episode 17, the Going Merry is home to his band of pirates. Originally intended to be Kaya's, she gave it to the Straw Hats after they saved her home of Shiroppu Village from Captain Kuro and his Black Cat Pirates.
Designed and created by Kaya's servant Merry, the ship
bears much resemblance to it's builder in it's sheep-headed
prow that decorates the stern (this is a bit of a joke because the Japanese word for butler is shitsuji and the word for sheep is hitsuji). It falls into the caravel class of ship, meaning that it is a light, small boat with twin masts. It is armed with four cannons although these are hardly used. Luffy had Usopp paint their pirate mark (a skull and crossbones Jolly Roger complete with none other than a straw hat) on Merry's main sail, giving the ship it's most distinctive feature. That and the three mikan trees that are set up mid-ship to remind Nami of her hometown.
The Going Merry has become a very important part of the story, so much so that it's almost a character of its own. Shown to have appreciated the love and respect from Usopp and the rest of the crew, Merry is revealed to have almost lifelike qualities coming to the aid of the Straw Hats at times and even mysteriously fixing itself when it is terribly damaged in the Sky Pier saga. Additionally, it is more than a means of travel for the crew, it's also their home. Although not technically counted, Merry is sentimentally considered a member of the group - their nakama.
Given a Viking funeral when it finally cracks under it's own weight in episode 312, the Going Merry is eventually replaced by the much bigger and more durable ship, the Thousand Sunny, created by new crew shipwright Franky.