Deep

Deep is the thirteenth episode of Ben 10: Ultimate Alien.

Plot
Underwater, a Magister Plumber named Pyke is searching for something. He finds a swimming object which happens to be Ultimate Aggregor who seems to defeat Magister Pyke.

Ben is surrounded by fans and tries to escape as Goop, but fails while Gwen and Kevin save him. Ben receives a message from Pyke about Ultimate Aggregor. They go to planet Piscciss to search for Pyke, but are attacked by a monster. They use the electrical gauntlets in their Plumber suits to defeat the monster, but in the battle, Kevin's helmet cracks.

With Kevin drowning, Gwen blasts him against the jet's side, causing him to absorb the jet's coating, saving from from being crushed by the water pressure, while a nearby fish is able to convert itself into a helmet for him so he can breathe. Pyke shows up and they go with him to find Ultimate Aggregor. Ben's helmet cracks when they battle many sea creatures and he tries to transform, but becomes Humungousaur. He scared them off and turns into AmpFibian.

They pass the guards once they explain their Plumber business, and go to the core of the planet, where it looks like Ultimate Aggregor is attacking. The core has air in it while, Pyke uses a water helmet to breathe. But a tremor occurs and Pyke is crushed by a rock. While Gwen stays to help him, Ben and Kevin go on, but find Ultimate Aggregor grabbing the planet's core piece that keeps it together.

It turns out the anti-gravity multiplier that holds Piscciss together is the second piece of the Map of Infinity, which Paradox disguised it so no one would not suspect. Ultimate Aggregor leaves and Big Chill chases him. Gwen, Kevin, and Pyke with the core guards. Big Chill turns into Ultimate Big Chill when the guards keep distracting him and his friends as the culprits for stealing the core piece. Ultimate Aggregor escapes Piscciss. Ultimate Big Chill, trying to prevent Piscciss from scattering into pieces, transforms into Goop, and uses his anti-gravity projector as a substitute, but it also sucks in Goop. Soon the water turns green and Piscciss pulls itself back together, with Goop reverting back to Ben and being saved before he drowns. Pyke thanks them for their help and Kevin wards off the fish that was used as his breathing helmet much to his sadness while Gwen consoles him.

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Kevin Levin
 * Magister Pyke
 * Little Fish
 * Piscciss Volann Core Guards

Villains

 * Ultimate Aggregor
 * Sea Monster

Aliens Used

 * Goop (x2)
 * Humungousaur
 * AmpFibian
 * Big Chill
 * Ultimate Big Chill

Errors

 * At the beginning of the episode when Magister Pyke is chasing Ultimate Aggregor, there's a lot of rocks shown floating around. But later in the episode, there aren't any rocks at all, excluding the core.
 * When Pyke got his water helmet, Kevin was shifting between his normal form and his metal form.
 * When Big Chill is chasing Aggregor, two Piscciss Volanns start to chase him, for a moment it can be seen that the one on the right is wearing a Plumber's suit, not the usual guard uniform.
 * Kevin says S'ok, I took pictures and displays a cell phone but when he and Gwen rescued Ben, he did not take pictures.
 * The whole time Goop was pulling the planet together, Pyke did not have his helmet on and yet showed no discomfort.
 * When Ben transformed into Humungousaur, the palms of his hands swapped between the color of his stomach, and the color of his back and arms.
 * When Goop kept the Anti-Gravity Projector, he didn't fall into a puddle like he usually does.