Dai-Gunkai

The Dai-Gunkai (ダイガンカイ, Daigankai?), rivaling the Dai-Gunzan in terms of sheer bulk and apparently much lengthier, is an aquatic Gunmen fortress resembling a centipede, which served as Adiane's flagship. The primary utility of the vessel is its aptitude for sea travel. The "kai" in the name can be translated as "sea", referring to it being an ocean-based unit.

Role in the show
The only appearance of the Dai-Gunkai in combat was in Episode 12, when it ambushed the Dai-Gurren while it was crossing the ocean on its march to the Helix Empire's capital. As Dai-Gurren futilely attempted to attack the submerged ship, Adiane gave command to Viral, having decided to personally confront the humans in her Sayrune.

With Adiane running interference, Viral sent Dai-Gunkai to cut off Dai-Gurren's flippers, before grabbing it from below and attempting to drag it underwater. The scheme was thwarted, however, by Gurren Lagann, who escaped Adiane and used a drill like a waterscrew to push Dai-Gurren back to the surface, ripping off Dai-Gunkai's claws in the process. After bringing the Dai-Gurren back to the surface, the Gurren-Lagann obliterated the Dai-Gunkai by drilling through its entire body, with Viral as the only survivor.

Weaponry and capacities
While it seems to only be able to travel in a body of water, the Dai-Gunkai's first appearance was marked by a sudden deluge over the battlefield, suggesting that it may have the ability to divert-or even create-large volumes of water. Like a submarine, the vessel can travel deep underwater and withstand crushing pressure. The manouvrability and the power of the Dai-Gunkai underwater are impressive, as it is able to easily pull the Dai-Gurren deep down into the ocean.

Its main weaponry consisted of torpedoes guided by dolphin Beastmen and two massive pincers, which could tear even the Dai-Gurren's hull. It also possessed a cannon in each eye, which were apparently for surface combat.

Movie Version
In the movie, it has a slight redesign-likely done for the land combat it would be partaking in. It has a larger, more defined lower section than the version seen in the anime, and could defeat Dai-Gurren in a wrestle of brute force. It eventually combined with the other Dai-Guns to create Do-Ten-Kai-Zan, but was quickly destroyed by Team Dai-Gurren.