Octonaught (also spelled Octo-Naught in the same story) is a Badnik/mech controlled by Captain Claw. Found in the Mobian Channel, Octonaught is responsible for attacking anybody who dares to cross the ocean without answering to its master.
The ship's usual form is of a giant octopus, complete with eight metallic tentacles that can freely attack foes. When the situation calls for it, these tentacles can detach from the main body and can individually harass an enemy, hitting them or dragging them underwater so they will drown. Not content with that power, the Octonaught is equipped with an automatic gun that can fire at any angle. Finally, the bottom of the ship is electrocuted, giving foes who think of using a sneak attack a nasty shock!
Octonaught was destroyed by its own driver when Captain Claw tried to shoot down Knuckles the Echidna. The echidna attempted to dodge the Badnik's weapons by hiding on large stone stacks in the ocean but Claw used the guns to bring down these formations. Eventually, Claw shot down the last platform, not realising it was towering directly above him. Debris from the attack landed on the Octonaught, crushing it and rendering it unusable. Fortunately, Knuckles had a way to get around this, forcing Claw to get out an oar and use the Octonaught as a simple boat.