The Grand Sea Pirates is the name of a pirate crew under the command of captain Sigfreid. The crew is considered large, at 900 crew mates. Though not a very active crew, the crew has shown itself capable of astonishing feats. The Grand Sea Pirates control both the island of Albaneue and Jestato, and many their top members are known to have competed with notable figures in world history.
Notably, every ranked member of the crew is known to be able to use Haki to some extent.
The crew's Jolly Roger is unknown, if they have one at all.
The captain of the crew, Sigfreid, is rather indiscriminate with who he adds to the crew, and often just recruits people from other pirate crews that he's defeated. The entire crew is about 900 strong, but the true strength lies in its' ranked members.
The total power of the crew is largely unknown. Marine Vice Admiral Garp once referred to them as a "Pain in the marine's side, but nothing more", implying that he didn't take the crew too seriously. Whitebeard, however, acknowledged their captain once despite defeating him, and believed that they would become a terrifying force if they wanted to.
Both of these remarks are probably due to the crews' lack of action in over five years. Despite the captain's high bounty and list of crimes, the crew as a whole has not made any public incidents worth mentioning. Regardless, Sigfreid alone was powerful enough to defeat entire crews of pirates, such as the Straw Hat Pirates (pre-time skip), the Caveyard pirates, and several marines.
It is well known that four of the ranked officers in the crew had well-known rivalries in the past.
Sigfreid has clashed with Admiral Kizaru on multiple occasions, often ending them in draws. He calls Kizaru "Borsa-kun~" whenever they meet. He also battled Whitebeard once in the past. Storm is known to have fought against Kuma back when he was a revolutionary, and may know about his deal with the marines.
Zomboy was once a notorious pirate who went on murderous rampages across the grand line until he was defeated many years ago by Gol D. Roger. Rogg is implied to have battled Roger in the past as well.