They Lurk Below

They Lurk Below is the twenty-third episode of Ben 10.

Plot
A jet flies by, and inside, Ben is excited that Grandpa Max invited him and Gwen on the trip. It belongs to a billionaire, Donovan Grandsmith, who's one of Max's old friends and the jet seems to be headed to an underwater building entrance. They introduce themselves, though Donovan’s grandson, Edwin, doesn’t seem to be happy much. They head inside the elevator and they enter inside an underwater resort. The view of the marine life is magnificent and something to see, though Max is a bit worried, because the resort is built right in the middle of the Bermuda Triangle.

As they enter the main building of the resort, Ben and Gwen are absolutely excited to see the sights. Edwin continues his rude behavior toward his guests. Suddenly, the lights flicker, and the surge causes the fans outside to reverse. The employee outside was in danger, and to make it worse, great white sharks were coming and circled around him. Ben comes to the rescue, hoping to transform into Ripjaws, though into Grey Matter instead. The Omnitrix’s flash seemed to have attracted Edwin’s attention, but he wasn’t too interested in it and continued to speculate the man outside.

Luckily enough, the fans reversed again and it caused Grey Matter and the man to be pushed out into the indoor pools, though Grey Matter flew into the air. Donovan told them that he had to increase his salary to make sure that he won’t tell anyone about the event. Donovan wanted to talk to Max more, so he tells his Edwin to give Ben and Gwen a tour of the place, though the lot of them didn’t see much interest in each other, after Edwin’s demonstration in treating his guests.

As Edwin gives the tour, an indoor “beach” revealed that he was a good swimmer. Ben mocks him. Then they find a giant submarine, which Edwin offered for them to ride in it. This troubles Gwen, though Edwin looks at her, giving a look that would indicate his answer to such a useless question. Meanwhile, Max has his own tour of the place. Donovan explains how the power is taken from volcanic vents. What puzzled Max is what was behind a container-looking machine, though Donovan may be hiding something. He tells his employees to turn on a light that can be seen for over 500 feet above sea level, which demonstrates how much energy the plant generates. To finish the tour, Donovan finds that the Under Sea Manta Ray is gone and knew that Edwin has taken it.

While the kids are inside the manta ray, they speculate the underwater sea life, and Gwen is surprised to see fish that looked prehistoric, they looked a lot like Ripjaws. Their enjoyment ends however, when all of a sudden, mysterious Cyber Squids attack the giant underwater machine. What makes it more strange is that Gwen finds that the ground is glowing below them. The Cyber Squids keep attacking, and was able to break the glass dome of the submarine, making their current position to be in danger.

Edwin pilots the manta ray into underwater mines, which made the situation worse, though they were able to get through with ease. The Cyber Squids follow, while Edwin tries to contact for help. Ben gives a signal to Gwen that he’s going to use the Omnitrix, and Ben heads back to activate it. He transforms into Ripjaws, and he heads out to fight the Cyber Squids. Edwin’s distress call was answered by Donovan, though he doesn’t believe Edwin, until Max tells him that it wasn’t a joke, until many more were headed up the resort.

Ripjaws fights even more Cyber Squids, and he seems to be getting through them easily. However, the Omnitrix gives its timing out signal, alerting Ripjaws that he's about to revert to Ben. He's in danger, especially when the situation gets worse when he has difficulty opening the door to the inside of the submarine. Max and Donovan head to the opening where the submarine enters, and were able to get in, though the problems get only worse when a Cyber Squid destroys the glass dome of the resort, making the water pour in and flood. Ben has managed to get back in safe. Edwin seems to know what Donovan was keeping from what Max wanted to know about, which probably lured the Cyber Squids into the resort. Donovan confesses, and he said that he found a strange underwater power source, and he took it for his own use after the resort was in danger after the volcanic vents were unsuccessful. The resort was flooded, and there was no turning back when they started to head back into the surface. Unfortunately, some Cyber Squids tear their ride in half, sending Ben, Gwen and Edwin back into the flooded resort, and in danger of being flattened.

Fortunately, Ben transforms into Stinkfly, and carries them into safety, though end up inside the flooded resort. Edwin has figured out the secret, as Ben is always gone when a good alien shows up. Meanwhile, Stinkfly’s wings are wet, so they need to find a way to the power core. Gwen finds a nearby vent where they can travel in. Above sea level, Max and Donovan try to contact either them and for help, though it seems to have no luck, as the navy would take time to travel to their location, while the lines in the underwater resort make communication between them and the kids impossible. While the kids travel the vents, it falls into the water, though they end up in another area where there are speedboats available.

They travel the floods with speed, getting away from the aliens. Meanwhile, Donovan wonders how Edwin is doing, and he asks Max how he treats his kids. Donovan seems to want some advice from Max, as he seems to have little bond between him and Edwin. Though the kids may be a screw up at times, Max tells Donovan to let them be and give them the opportunity to do their own things, which explains why the kids follow him around and look up to him.

Inside the resort, Ben, Gwen and Edwin find the core, and Edwin tells them that they should reverse the polarity of the connections to make the whole resort implode, with the Cyber Squids in it. Ben transforms into Upgrade and merges with the submarine to get out of the area. Successfully, they are rid of all of the Cyber Squids, but with the resort is gone with them.

They arrive at the surface, and the grandfathers are grateful for their grandchildren's’ safety. Edwin tells Donovan that the resort is gone, though he seems to be okay with it. He has another plan and he said that it's going to be on the moon, Ben, Gwen and Max laugh to his invitation.

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Max Tennyson
 * Edwin Grand Smith (first appearance)
 * Donovan Grand Smith (first appearance)

Villains

 * Cyber Squids (first appearance)

Aliens Used

 * Grey Matter (accidental transformation; selected alien was Ripjaws)
 * Ripjaws
 * Stinkfly
 * Upgrade

Errors

 * Grey Matter acted as if he couldn't breathe underwater, even though he can.  Though, considering Ben's lack of knowlage on alien species at the time, it is possible he was unaware of that fact.

Trivia

 * The "prehistoric" fish as pointed out by Gwen, resemble a fusion of an Ectonurite and a Piscciss Volann.