Ship Design and Appearance
The Polar Tang is a submarine that is yellow with a light green underside lined with torpedo cannons. Unlike most pirate ships, it is mostly made out of metal and runs on engines instead of sails. The upper decks are made of wood, though, and there are two tall masts on both the front and back levels. These two masts have retractable sails to be used when its engines are not activated, with the front mast having a rectangular dark-colored sail bearing the Heart Pirates' Jolly Roger on it. Circular windows line the craft, and the Heart Pirates' Jolly Roger and Law's "DEATH" tattoo are plastered on the exterior. There are also lights resembling streetlamps on the outside in order to allow sight underwater.
Inside the ship is an advanced medical room, where Law can perform operations on patients.
The ship was built by Wolf on Swallow Island, using money he gained from finding Captain Ladoga's treasure, and named it the Invincible Hanamaru. He used it occasionally patrol the island, but it remained unknown to the residents of the island.
When Artur Bacca attacked Pleasure Town, Wolf, Law, Bepo, Shachi, and Penguin used the submarine to sneak attack the pirate, breaking through the floor of the Pleasure Town Temple of the Sea God. Once Bacca learned that Wolf had used Ladoga's treasure to create it, he planned to dismantle it and sell the pieces.
When the Heart Pirates were leaving Swallow Island, Wolf gifted them the submarine, with Law renaming it Polar Tang. Wolf drew the Heart Pirates Jolly Roger on the side and the crew left the island, taking the ship with them.
Concludes non-canon section.
Summit War Saga
The Heart Pirates came to Marineford on the Polar Tang during the Summit War of Marineford in order to save Monkey D. Luffy. They fled Marineford with Luffy and Jinbe, managing to evade Aokiji's Ice Age and Kizaru's Yasakani no Magatama attacks.
Later, Law turned the recovering Luffy and Jinbe over to Boa Hancock on a stolen Marine ship. They traveled to Amazon Lily and the Polar Tang was docked at a small beach while Law waited to return Luffy's hat. However, Law and his crew departed after Silvers Rayleigh arrived and Law passed the hat to the former pirate.
Four Emperors Saga
After the Ninja-Pirate-Mink-Samurai Alliance was formed, the Heart Pirates prepared to set sail for Wano Country in the Polar Tang along with some of the Straw Hat Pirates and the Kozuki Family retainers.
Wano Country Arc
Later on, the submarine was used to transport some of the Scabbards (Inuarashi, Kikunojo, Raizo, Ashura Doji, and Kawamatsu) to the back of Onigashima. When the submarine got close enough, it rose to the surface and Law teleported himself, Bepo, Shachi, Penguin, and the Scabbards with them to Onigashima's back entrance. Once they left, the submarine submerged back underwater.
- Tang, or surgeonfish, are members of the family Acanthuridae that are characterized by their scalpel-shaped spines, fitting the theme of the Heart Pirates.
- The Polar Tang also shares its name with two individual submarines (the USS Tang (SS-306) and the USS Tang (SS-563)) as well as the Tang-class submarines used by the United States.
- The Polar Tang is quite literally a yellow submarine, this could possibly be a reference to the 1969 album ’Yellow Submarine’ by The Beatles.