Heart Pirates

The Heart Pirates are an infamous and notable rookie pirate crew from the North Blue and introduced on Sabaody Archipelago around the time the Straw Hat Pirates arrived there two years ago. Their captain, Trafalgar D. Water Law, is a member of the Worst Generation and a former Shichibukai. They are currently in an alliance with the Straw Hat Pirates, Kozuki Family, and Mink Tribe with the goal of taking down Kaido of the Yonko.

Crew Members
The crew consists of twenty-one members, all but two of whom wear a pale-lilac boiler-suit apparel with the crew's Jolly Roger emblazoned on the left side of the chest, aside from their captain and Navigator. When Jean Bart first joined the crew, he merely wore a black shirt after changing out of his slave's clothes, but after the time-skip, he is shown to have adopted the same outfit as the rest of the crew. Their uniform is notable for being similar to the ones worn by the World Noble's slaves who were working in Tequila Wolf, with the only notable differences are the color and the Heart Pirates' have their jolly roger on their suits. They also have a single female crew member.

It appears that Bepo, Shachi and Penguin are all proficient in martial arts, in which they all seem stylistically similar. Their captain is also the doctor on-board.
 * Trafalgar D. Water Law
 * Bepo
 * Shachi
 * Penguin
 * Jean Bart
 * Ikkaku
 * Uni
 * Clione

Allies and Affiliation

 * Wolf
 * Straw Hat Pirates
 * Ninja-Pirate-Mink-Samurai Alliance

Crew Strength
They are a strong crew for them to have made it all the way to Sabaody Archipelago, and have a captain who is a member of the Worst Generation. With the addition of the new member, famous pirate captain Jean Bart, the crew may have grown even stronger. All crewmembers were able to withstand a blast of Haki from Silvers Rayleigh, though Shachi stated that he almost passed out, which may indicate he is slightly less powerful.

Like the rest of Supernovas, they were able to escape Kizaru's raid. They were also able to make it to Marineford, where the war was taking place not long after leaving Sabaody Archipelago. They also assisted the minks in fighting against an invasion by the Beast Pirates led by Jack.

They also seem to have incredible medical expertise, as their submarine is equipped with various advanced medical equipment including a complete operating theater, and their captain is a surgeon capable enough to heal Luffy and Jinbe while the former was on the verge of death and the latter was brutally wounded by Akainu's magma.

Given that their captain is a former member of the Shichibukai, it is likely that the crew's reputation and strength have increased as well.

The crew on Law's behalf has become allies with the Straw Hat Pirates, making them such a dangerous alliance that it even jeopardized and ultimately cost Law's position in the Shichibukai.

Ship
The Heart Pirates use a submarine called the Polar Tang as their main mode of transportation.

The vessel seems to display considerable speed and maneuverability when submerged, as seen when it completely outpaced Aokiji's Ice Age, and evaded Kizaru's Yasakani no Magatama. It also seems that the Polar Tang can go through the Calm Belt since it left Amazon Lily without needing to be accompanied by the Kuja Pirates' ship.

Despite the fact that it works like a submarine, its design is similar to a ship as it has a mast and lamps on the outside. Also, on the side of it is the Jolly Roger of the Heart Pirates with the word DEATH, referring to the tattoos on Trafalgar Law's hands.

From the inside, the Polar Tang seems to be well-equipped with medical apparatuses and life-support systems all stored in the sick bay.

Trivia

 * In the Japanese fandom, Penguin and Shachi were often called "Penguin" and "Casquette". The former after the word on his cap, and the latter after the Japanese name of the type of hat he wears.
 * The Heart Pirates' Jolly Roger resembles a virus, a suitable choice considering Trafalgar Law's profession and his epithet: "Surgeon of Death".
 * Also their jolly roger is a "smiley", as first seen used by Law's former superior Donquixote Doflamingo. But unlike Doflamingo's smiley, theirs does not have a "cancel" sign across it. At the end of Chapter 766, Corazon wanted Law to remember him smiling if he ever thought about him in the future, therefore this is most likely the origin for the smile on the jolly roger.
 * Before the timeskip, all the crew members except for Law, Bepo, and Jean Bart had their face obscured by some kind of hat.
 * Law having a submarine for a ship might be a reference to the Trafalgar class of submarines.
 * The name "Heart Pirates" have several possible origins.
 * It is likely a reference to Doflamingo's promise to give the "heart" position in his organization to Law.
 * It may be a reference to Law's Mes technique, in which he literally takes the heart from his opponents.
 * The crew may also have been named in honor of Corazon (Spanish for heart), who was Doflamingo's younger brother, Law's benefactor, and the previous owner of the heart seat in the Donquixote Family. This is a fact that particularly infuriates Doflamingo, believing it to be a curse derived from his younger brother's kindness.
 * Additionally, the Ope Ope no Mi was shaped like a heart, further referencing the heart theme.
 * In an SBS, a fan noted that the crew seem to have a "cold climate animal" theme: Bepo is a polar bear, Penguin and Shachi are named after polar animals (although orcas are found in all oceans) and Law's hat is like a larga seal. Oda acknowledged this and also noted that Law was represented by a snow leopard(another cold climate animal) in Toshio Asakuma's Animal Figurine Collection. Their submarine's name continues this pattern.
 * In a later SBS, three additional members names are revealed to follow that theme: Ikkaku means "narwhal", Uni means "sea urchin", and Clione is a genus of sea slugs.
 * Jean Bart is the only known member not to follow this theme.