Although having the name "Submarine Eggman", it travels through lava instead of water. It resembles the Eggmobile with a gun mounted on top. Being mostly grey, it has black and yellow stripes and orange headlights.
The boss battle takes place on three small pieces of land with lava in between each area of land. Dr. Robotnik begins the battle by rising up from the lava on the right side. This Eggmobile has a nozzle at the top which shoots fire. After Robotnik shoots, he sinks back into the lava, and two fireballs come out of the lava onto the land. This temporarily sets the areas on fire. Robotnik returns in a few seconds, and the process repeats until he is defeated. Like the other Eggmobiles in Sonic the Hedgehog 2, Submarine Eggman takes eight hits to be defeated.
- Unlike other bosses in the game, Super Sonic cannot attack Robotnik by just standing around.