Ganzack Pirates

The Ganzack Pirates were a group of pirates led by Ganzack. They only appeared in One Piece OVA.

Ship
The Ganzack Pirates possessed a massive warship built by Ganzack to achieve his goal of conquering the Grand Line. The ship is a massive, complex machine. Built beneath his fortress by the enslaved islanders, Ganzack unveiled the warship after putting down a rebellion. Ultimately, however, the joint forces of the islanders with Luffy, Zoro, Medacka, and Nami defeated Ganzack and sank the ship

The warship was huge. In addition to spikes and cannons it has several special weapons. In the bow of the ship there was a chamber for Ganzack's Seamonster. On top of the fortress was a massive dynamite gun, a weapon was of mass destruction.