He becomes more interested in being a pirate than a medic (stating that he wanted to be a 'real' Octonaut like Kwazii). With half the crew stranded in a rock pool due to a low tide, Peso and Tweak help to remove a stuck hermit crab from the shell he has outgrown. The Octopod's periscope breaks off during a storm and lands up on a beach, lost amongst other marine debris.

While diving down to the Midnight Zone, the Octonauts are attacked by bomber worms and are enlisted to rescue an injured member of their troop. It is built to look like a dragonfly, to soar above the sea, and watch the animals that hop in and out of the water, an amazing sight to see! After failing to rescue them with the GUP-C's icebreaker and the GUP-D's drill, they enlist the help of some bowhead whales whose massive heads can break through thick ice. Most have appeared in the episodes and specials of the series, and at least 5 have appeared in the two movies ( The Underwater Caves of Sac Actun , Octonauts and the Great Barrier Reef and the The Octonauts Movie: The Ring of Fire.Then there is piranha mode where the tail of the gup becomes a separate vehicle and can chomp through even the largest rocks. It may be a deep-sea excavation Gup that may work around the Deep Sea Octolab in the Mariana Trench. Then he and the Octonauts must help their old friends the coconut crabs discover who's stealing all their coconuts. She tells them to Kwazii's surprise that the missing male seahorse is about to give birth to baby seahorses!

The Octonauts are helped by Shellingtons's sister, Pearl, another sea otter and scientist, and her newborn son, Periwinkle. As Tweak tests the Gup-X deep down in the Midnight Zone, a yeti crab cuts a vital electrical wire in the ship and cuts off all power, endangering himself and the Octonauts. Captain Barnacles' niece and nephew Ursa and Orson are going to get their Polar Scout Badges when they spot three walrus pups on a drifting floe which is on a crash-course with two icebergs. When Peso gets stranded on a beach with a mass of poisonous snakes after a terrible storm, one of the yellow-bellied snakes has a splinter of driftwood stuck in her scales, and Peso has a broken flipper (According to the UK version, meanwhile the US Version indicates that he got stung). In a rare journey into fresh waters (a river), the Octonauts follow some migrating eels and help an injured eel on his difficult journey when he gets stranded from the others.

When Peso's patient, a remora fish, mysteriously disappears, the Octonauts enlist a unique undersea detective - a harbour seal. The Octonauts travel for Christmas to Professor Inkling's childhood home, a seamount, but soon get involved in a rescue mission when a rockslide endangers a rare 500-year-old golden coral and traps Professor Inkling's nephew Squirt. The Octonauts follow a strange song to a lonely humpback whale who is alone because he does not sound like the other whales! When Dashi is swallowed by a whale shark, mistaken for a cave, the Octonauts venture inside of him to come and rescue her.

Peso and the gang try to repair a reef by replacing bleached corals, but a pod of playful dolphins make mischief for them until they discover that helping can be fun too. It can split into five separate Gups, so everyone can drive in different parts, and it can combine into a giant robot. They have to help him because if nobody understands him, he won't find the way to the feeding ground.

When the Octopod cruises underwater to Captain Barnacles' homeland, the North Pole, it gets trapped in the Arctic sea ice, but one of Barnacles' old friends, Boris the narwhal, helps them break through the ice with his long tusk. Shellington's nephew Periwinkle even made a toy based on this gup, which, according to his mother, makes a "lovely back scratcher". The eyes of the Gup can release and become Gup-Q Scooters for traveling into small crevasses that the large Gup cannot fit in. A jawfish father has lost the eggs he was brooding and the Octonauts must bring them safely back to him!