The Secret Treasure of Potion Ocean is the twenty-fifth Moshi Monsters mission and the fifth mission of Season Three.
On the beach, Jaunty Jack and Handy Van Hookz can be seen. Talk to Jaunty Jack. Apparently, he is wearing a new hat. When you ask if he's found the treasure map piece yet, he says that his hat got blown away and he made himself a new one and he didn't find the map piece. Now, talk to Handy Van Hookz. He has found the map in a pond but he can't grab it because the hooks he wears are missing and there is a large lobster or crab sticking its claw out of the pond, but if he had his hooks back, he could reach in and get it. Apparently, two fish stole the hooks. Find and click on a barrel of eyeballs, open your inventory (the blue pouch on the far right) and drag the eyeballs into the net. This catches one fish. Click the fish, open your inventory and drag the hook onto Handy Van Hookz. He finds a piece of the map in a bottle. Click the map piece to retrieve it. Now, click on the blue starfish, open your inventory, and drag it into the net. This lands you the blue fish. Click on it. Then, open your inventory and drag the hook onto the fishing rod, then drag the rod onto the hat in the sea. Jaunty Jack thanks you, then gives you the new one which turns out to be part of the treasure map. Now, click the hook on the ground, open your inventory and give it back to Handy. He gives you an E.P.I.C.S. award. Now, click the ship to go back.
Open your inventory and drag the pieces onto Captain Codswallop to hand them over. Then, use the mouse to put the pieces together. The pirates start to read the map, but a hook steals it. Captain Codswallop is determined to get it back. Then, a ship with Commander Sassafras on it sails off and a giant sea monster takes the Gooey Galleon.
Jaunty Jack then goes back into the cabin and asks for some items to help fight off the squid. Click the stuffed shark and collect a chicken leg, then the cat cage and collect a key. Open your inventory and use the key on the cupboard. It sort of works, but you'll need another one. Find a key under the bed, open your inventory and use it on the cupboard. You will find a feather on the skeleton. Jaunty Jack is satisfied and goes back outside. Open your inventory and drag the feather onto Handy Van Hookz, who tickles Squid Vicious. Open your inventory and hand the chicken leg to Jaunty Jack. It attracts fish, which tickle Squid Vicious and he's now only holding on with one tentacle. Talk to the Moshling who's just woken up. Apparently, his name is Uncle Scallops and he is cranky because he thinks Squid Vicious is being too noisy and it's keeping him awake. If you ask for help, he reluctantly agrees to help you if you give him something that will help him sleep. Find two sponges to block his ears with, open your inventory and drag them onto him. Then, he pokes Squid Vicious's tentacle with his pitchfork. It works and the ship floats back up.
- Accessory-Wearing Cartoon Animal: The Super Moshi wears its cape, belt and mask, the pirates wear their pirate accessories, Uncle Scallops wears a crown and Squid Vicious wears a collar.
- A Day in the Limelight: This mission focuses on Sassafras and the ghost pirates.
- A Dog Named "Dog": Played with for Squid Vicious. He has "Squid" in his name and he is a squid but he also has "Vicious" in his name.
- Alliterative Name: Jaunty Jack.
- Big Bad: Sassafras causes the main conflict by stealing the treasure map, although Squid Vicious also played a big part in causing conflict.
- Blue Is Heroic: The Super Moshi wears a blue utility belt, Captain Codswallop is blue, and Uncle Scallops's tail is blue, and they all helped save the day.
- Does Not Like Spam: Apparently, Uncle Scallops (and his species in general) don't like ketchup.
- Dressed to Plunder: The ghost pirates and Sassafras all wear pirate hats, eyepatches etc.
- Fully Dressed Cartoon Animal: Sassafras wears his sailor outfit.
- Grumpy Bear: Uncle Scallops and his species are some of the few grumpy characters in Moshi Monsters aside from the villains.
- Hook Hand: Handy Van Hookz has two literal ones, which he loses in the first part.
- Jerk with a Heart of Gold:
- The pirates like to steal treasure, but they are willing to let the owner have it if they're insistent.
- Uncle Scallops is a bit grumpy (and apparently his species in general like to poke people with their forks) but he's willing to help out.
- Meaningful Name: Squid Vicious is a vicious squid and Handy Van Hookz has two hooks on his hands.
- Mister Strangenoun: Sassafras's name is a word, Jaunty Jack has "Jaunty" in his name, Captain Codswallop has "Codswallop", Uncle Scallops's name is two words as is Squid Vicious's, Mr Mushy Peas has "Mushy" and "Peas" and Handy Van Hookz has "Handy".
- Pirate: The mission focuses on a crew of ghost pirates.
- Pirate Booty: The Ultimate Treasure is in a huge treasure chest.
- Red Is Heroic: Played straight for the Super Moshi who wears a red cape and mask but inverted for Squid Vicious, who is red and is mean.
- Red Is Violent: Zigzagged for Squid Vicious. Although he doesn't do anything really violent (trapping the pirates under the sea didn't hurt them and he might not have realized that he was endangering the Super Moshi), he is quite mean and he did threaten to be even worse if they tried to get the treasure again. And, of course, he's red.
- Superheroes Wear Capes: The Super Moshi wears a cape, Captain Codswallop even tells them to "hold onto [their] cape" at one point.
- Talk Like a Pirate: The pirates use words like "be", "ahoy", "ar", "ye" and "shiver me timbers."
- The Undead: All the pirate crew are ghosts. Exploited, as that means they don't have to breathe so they can do the dirty work under the sea.