Noah

Noah (ノア), also known as the "Ship of Promise" (約束の舟), is a giant ship in the Fishman District that was created long ago by the people of Fishman Island. It is described as mysterious and is half of the size of Fishman Island.

Appearance
Noah is an ark that is much larger than any other wooden ship seen so far in the series. It has several winches jutting out from holes in its hull on either side. It seems to be held in place by large chains on the winches. There is a large dip in the guardrail on both sides where one would put a ramp or staircase to allow for boarding and deboarding the vessel. The bridge is at least four stories high, has a curved roof, and the windows are covered with what look like either curtains or prison bars. The figurehead is round and curled outward at the top. It seems to have accrued a large layer of sludge or moss on the railing and figurehead, as well as what look like barnacles on the bottom of the hull.

History
The giant ship is hundreds of years old and it was part of a failed attempt to move into the human world.

Hundreds of years ago, the people of Fishman Island promised someone described as "a great man" to keep Noah safe on the ocean floor until a certain day arrives, and the people have been doing just that.

After being rejected by Shirahoshi, Vander Decken IX, in a fit of rage, threw the entire ship with his powers at the mermaid princess, in an attempt to end everything.

The ship has since appeared on Fishman Island's horizon. When Neptune sees the ship he becomes incredibly nervous. Fukaboshi asks him why he is so nervous about an old piece of history. Neptune responds that absolutely no one is allowed to move the ship until a certain day comes. He explains that hundreds of years ago a promise was made to a "great man" that the ship would be kept on the ocean floor until the promised day.

The ship then continues onto to Fishman Island, threatening to pop the bubble around the island. When Wadatsumi fell off the ship, the islanders knew it was Decken's doing. Decken, on board of the ship, declared the end of everything when Shirahoshi left the plaza to guide the ship away. Hody Jones climbs onto one of the ship's enormous chains and Luffy gets ready to launch from Sanji's leg onto the ship, both in an attempt to stop Decken. When Shirahoshi escaped from Fishman Island's bubble, Noah turned away from the island. When Shirahoshi swims up to the surface Noah flies vertically, up to the surface. Jones gets on deck and impales Decken.

Hody intends to take advantage of the situation by allowing the ship to crash into Fishman Island while it is hanging above it; by killing Decken and deactivating his powers, the ship will lose its hold and fall. This led to a fight between Hody and Decken, with the former winning. Decken fell onto the cabin of the sideways ship, though the ship did not fall, meaning Decken is still alive. However, Decken falls unconscious, negating his power and control over Noah as it descends towards Fishman Island. There is now a plan in place to launch a bubble of air at Noah in order to allow breathing while on the ship.

Trivia

 * The ship is most likely named after the story of Noah's Ark.