The Mega Octus[note 1] is an object that appears in Sonic Mania. It is a giant, Octus-based submarine created by Dr. Eggman that was used by the doctor himself to battle Sonic and his friends.



Like its name implies, the Mega Octus is a submarine designed to resemble a giant pink Octus Badnik. It thus has a giant round head featuring cartoonish eyes with black pupils, an open snout for a mouth, giant gray corkscrews for ears, and a golden neck collar. It also has a golden hatch on top of its head, and numerous tentacles, each one made up of a string of pink orbs. On the tip of each tentacle is also a specific weapon.

Features and abilities

The Mega Octus' tentacles have incredible strength, enough to easily crush metal bridges and moving entire metal platforms. Its tentacles also come equipped with various weapons, such as laser guns, bullet shooters and claws. In some cases, it can even detach its tentacles and fire them as flexible spears.


When Sonic, Tails and Knuckles reached the end of Oil Ocean Zone, Dr. Eggman used the Mega Octus to crush the bridge the heroes had just crossed, leaving them stranded on the plaforms in the oily surroundings. Eggman proceeded to attack Sonic and co. with the Mega Octus, which ultimately ended up getting damaged by trio and sinking into the oily sea with Eggman.


The Mega Octus is the second boss of Oil Ocean Zone and the eighteenth overall boss of Sonic Mania. It is fought with Sonic, Tails or Knuckles at the end of Oil Ocean Zone Act 2.

Boss guide

The boss arena begins as a row of three large platforms over an oil pool with bridges between them. The battle begins when the Mega Octus' tentacles emerge from the oil and wrap around the leftmost and central platforms, pulling them beneath the oil and destroying the bridges between them. If the playable characters are on the platforms when they are pulled under, they will be pulled down to the bottom screen boundary and lose a life, though this can be avoided by getting off the platforms before they reach that point.

Once the platforms are gone, the Mega Octus' main body will surface from the oily sea. Dr. Eggman will then open its hatch to check the outside situation. After a few seconds, the doctor will get back inside, and the Mega Octus will dive back down again. While the boss is above the surface, the player can damage it with a Spin Jump.

Once the Mega Octus' main body has submerged, the platforms it pulled beneath the oil will rise back up into their original positions, giving the player more firm ground to stand on. A detached tentacle with a spiked tip will then emerge from the oil in an arc, go over the platform the player was standing on, before submerging beneath the oil's surface. This tentacle will damage the player if touched, but can be avoided by simply jumping over it.

Next, a tentacle with a laser cannon at its tip will rise vertically from the oil. This cannon will turn towards the side of the screen the player is on and fire three shots towards them at varying heights, which can be either jumped over or ducked to avoid. If a laser is fired at platform height, it will temporarily ignite every passing platform. Once the three shots have been fired, the arm submerges beneath the oil again.

Following up on that, four tentacles will emerge from the oil. Two of these have spherical cannons on their tips that rise vertically from the oil and will shoot bullets diagonally towards the player (although the bullets can be deflected if the player is equipped with an elemental shield). Each of these tentacles can be defeated by hitting the spherical cannon four times, though destroying them is not necessary to defeat the boss. The other two tentacles will wrap around the two platforms nearest the player (similar to the beginning of the boss fight) and pull them beneath the oil after a few seconds. Once the platforms have disappeared, the Mega Octus' main body will re-emerge from the oil and the cycle will begin anew. If any cannon tentacles remain, they will submerge whenever the main body dives beneath the oil and reappear each time the body is about to emerge (unless they have already been destroyed).

Landing eight hits on the main body will cause it to explode and sink beneath the oil, along with any cannon tentacles the player has not yet destroyed. Also, any submerged platforms will rise back up from the oil. The player can then proceed to the Capsule and finish the Zone.


Title Artist(s) Music Length
Ruby Delusions Tee Lopes
Sonic Mania OST - Eggman Boss 1


Sonic Mania Boss 19 - Big Octus01:39

Sonic Mania Boss 19 - Big Octus





  1. While not listed in any instruction manuals, the internal files in the PC release of Sonic Mania refers to this boss as "MegaOctus".

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