Unlike its counterpart from Hill Top Zone, this version of Submarine Eggman looks like a submarine-bullet-like machine. It has black and yellow stripes, as well as yellow bottom and side headlights.
Dr. Robotnik begins the battle by emerging from oil (giving the player an opportunity to attack) and then sinking back down. Next, Robotnik fires an air-borne attack spear at the player. Lastly, a gun will appear and fire three shots, the last of which will temporarily set the area on blue fire. (Both the spear and gun are attached to the submarine with long chains.) After this Dr. Robotnik will rise out of the oil again and the process will repeat. Like all Sonic the Hedgehog 2 Eggmobiles, Submarine Eggman II takes eight hits to be defeated. There is actually an extremely easy way to defeat this boss. If the player stays under a platform after attacking, then neither the gun nor spear can hit Sonic, then when Eggman resurfaces the player can continue their attack. Though if the player stops jumping while under the platform Sonic will sink.