The Sea Worm is the fourth boss in Metal Slug 6.
Most of the attacks aren't really that hard to dodge, but the Sea Worm will be constantly changing position, so be ready for a difficult fight. When its appears, depending on the difficulty, its will start off by spitting about 3 to 8 acid spit projectiles at the player, so go underneath its head to avoid these. Get away when he stops, though, as it will begin to spiral in a circle off the screen, and if the player get caught in the middle, the player die. Its will reappear on the right, spiralling towards you. Jump on to its body to avoid being skewered by its head. its floats upright, and takes a few more acid spit shots at the player. it then twists his entire body around, causing razor sharp wind to appear around each segment.
A well timed jump avoids this. Again, its will spiral in a circle, so make sure you're not stuck in the middle. Its reappears the left side, and will spit a trail of acid spits which goes up and down the stage. Hide under the Big Shiee to avoid this. After this, its just repeats until the player get rid of half his life. When it's flaming, he will spiral around the center, firing 5 energy blasts at the player. Just dodge over these or shoot them, and finish him off. If the Slug Flyer still available, this battle is made easier/harder depending on your skill.
- The Sea Worm is reminiscent of the Sandworms of Arrakis from the classic sci-fi novel series Dune, but a polar opposite, as this operates in a water environment. Both are also formidable.
- If the player still has the Slug Flyer, the Sea Worm will spit its acid much faster.
- The Worm Mecha from Metal Slug 7/XX resembles the Sea Worm in terms of movement and the ability to move its separate body parts.
- It is currently unknown if the Sea Worm is a combination of a mutated animal and a machine. This is evidenced by the Sea Worm showing smoke emanating from its body after it has been heavily damaged, and that more smoke spews out after its scales become damaged and chipped-off after suffering heavy fire.
- The ship present before the boss fight resembles the Big Shiee, just without its weapons. Some people think that the Big Shiee was attacked by the Seaworm.