US Title: "Depths of Danger"

The episode starts off with the military and president trying to figure out if Eggman actually managed to escape the attack on his base. The president orders them to find him at all costs. Meanwhile below the ocean surface rests the airship with Eggman telling them to be completely quiet so that they search team cannot locate them at all. With the team gone Eggman orders them to go out and repair the ship, both of them do not want to because they will rust.

At his house the group is getting ready to eat desert when Chuck comes in with official documents. They show their identity and wonder why they need all the documents. They learn that it is because they have been made citizens and with Amy looking at her picture she gets upset at the picture being used. Sonic comes in and he learns that he has documents too. He learns that it is a passport but he figures that he could go everywhere in about one day.

Later that day they decide to take off for a daytrip in the X Tornado. Chuck tells Tanaka to go keep an eye on Chris but not to let him know that he is being followed. Cream learns that they are going to the Sapphire Sea. Chris tells Amy that they are already flying over the sea. They look out to see crystal blue waters and both Amy and Cream celebrate getting ready to go swimming.

Tails then notices that the emerald is glowing and with sudden turbulence they decide that there is a chaos emerald under the water. Tails lands the plane and trying to keep a low profile they are unable to. The tourists suddenly chase after them making the group run for their lives. They finally stop on the beach and get upset that they cannot escape the crowd. They decide to have some fun but notice that Sonic is missing. Sonic though is in another location resting himself. Sonic knows that he cannot reach the emerald because he cannot stay underwater.

Elsewhere Cream and Amy play in the water while Tails and Cheese suntan. Back with Sonic he has an air tube in his mouth and goes to walk under water. However it hits a snag and falls below the surface. As Sonic tries to untangle it a crab comes out of nowhere and cuts the tube. With it grabbing onto Sonic he quickly goes above the surface screaming. The next plan is a diving bell which Sonic stops using because he trips with the bell landing on him.

Knowing that the only plan left is scuba gear, which they get for free. Chris learns that all the bills will be covered in a "Sonic budget". Chris is asked what they are going to see and changes the subject learning that a sunken ship is on the floor with a massive treasure. They leave the store with their gear and suit up. Putting on their gear they take off underwater with Amy and Tails helping Sonic swim under the water. Elsewhere Eggman’s fortress resurfaces and get ready to attack Sonic on his vacation.

Using the emerald to lead them they find the sunken ship the man at the store told them about. They locate the emerald to be somewhere in the ship and they get ready to go get the emerald. Above the water Bokkun arrives at the boat to only find Cheese napping on the boat. Back on the air ship Eggman is sun tanning when Bokkun arrives and plays the message back. Bokkun tells Eggman that he did not play the message when the message explodes leaving the doctor very upset.

Back at the ship the group finds the treasure buried and stands amazed at all the gold buried there. As they get ready to dig the grab resurfaces with the emerald in its claw. Sonic scares the crab into giving up the emerald as it runs off. As they get ready to celebrate Eggman appears and releases another robot on Sonic. He tells everyone to head back to the boat as Sonic takes on the robot himself. However underwater Sonic has no traction and is easily attacked by the robot.

Above the water Tanaka appears in a yacht and tells them to get aboard the ship. Chris stands a little stunned at Tanaka telling him that Chuck told him to come. Just then Sonic comes above the water and is grabbed by the tentacles of the robot. Appearing on a jet ski Sam appears and throws a rope towards Sonic. He grabs onto it and begins to water-ski around the robot. Tails flies in and throws a ring at Sonic. Using it he spin attacks the robot causing it to explode.

Back at the diving shop the owner is told of the ship and learns the remains where destroyed by Eggman. The shopkeeper is happy that the ship is real. The episode ends with Chris telling everyone that the man’s grandfather was the captain of the ship. They decide that they can finally enjoy their vacation and with Eggman very upset at his defeat.