| Season 4 | |
|---|---|
 | |
| Episodes: | 26 |
| Premiere: | September 23, 2015 |
| Finale: | May 28, 2017 |
| Next: | Season 5 |
This is the fourth season of the original Octonauts series. It debuted on September 23rd, 2015 in the UK on CBeebies. The season contains 24 11-minute episodes, as well as two 22-minute specials.
This season debuts the Gup-H (The Poison Dart Frogs), the Gup-I (Operation Deep Freeze), and the Gup-K (The Great Swamp Search). Also coming back more frequently from previous seasons is the Gup-S.
Episodes
DISCLAIMER: The list provided on this article is based off of the episode order and descriptions provided by Netflix. This has been done to streamline the organization of the episodes on the wiki according to continuity and the main platform Octonauts can be streamed on at the moment. Despite this change, the original air dates listed will still be according to the premieres on CBeebies UK, with the BBC websites as a reference. Not all air dates have been fully retrieved, so this will update over time.
| # | Title | Original Air Date |
|---|---|---|
| 1 | "The Walrus Pups" | September 29th, 2015 |
| Captain Barnacles regales his niece and nephew with a tale about saving walrus pups. | ||
| 2 | "The Mantis Shrimp" | September 30th, 2015 |
| Mantis shrimp on the reef have battle-ready claws. | ||
| 3 | "The Poison Dart Frogs" | September 23rd, 2015 |
| Kwazii helps a family of brightly colored, poison dart frogs. | ||
| 4 | "The Hidden Lake" | September 24th, 2015 |
| An icy adventure leads to a hidden lake in Antarctica that makes Shellington very happy. | ||
| 5 | "The Baby Sea Turtles" | September 28th, 2015 |
| The Octonauts carefully move baby sea turtle eggs away from danger. | ||
| 6 | "The Octopod Mystery" | September 25th, 2015 |
| The team discovers a mysterious creature living in an abandoned Octopod. | ||
| 7 | "The Tree Lobsters" | October 2nd, 2015 |
| A storm leads Peso to an island where he meets lobster-like creatures. | ||
| 8 | "The Convict Fish" | December 14th, 2015 |
| The reef is collapsing and all the animals flee except for the convict fish. | ||
| 9 | "The Great Swamp Search" | December 3rd, 2016 |
| The Octonauts journey to the Everglades to help Tweak’s dad, Ranger Marsh, find invasive species — including a Burmese python and her babies. | ||
| 10 | "The Crawfish" | December 3rd, 2016 |
| When a group of crawfish get sick, the Octonauts race to find a cure. | ||
| 11 | "The Surfing Snails" | September 6th, 2017 |
| Dashi tried to save surfing snails who are swept out to sea by a giant wave. | ||
| 12 | "The Baby Gator" | TBA |
| Kwazii adopts a baby alligator, but when it escapes there is big trouble. | ||
| 13 | "The Bomber Worms" | October 23rd, 2017 |
| While diving to the Midnight Zone, the team is attacked by bomber worms. | ||
| 14 | "The Flamingos" | December 3rd, 2016 |
| The Octonauts wade through a swamp to find a lost flamingo chick. | ||
| 15 | "Operation Cooperation" | September 27th, 2017 |
| Shellington crashes the Gup-D and teams up with a moray eel and a grouper fish. | ||
| 16 | "The Kelp Monster Mystery" | October 24th, 2017 |
| Dashi works with her little sister Koshi to solve a kelp forest mystery. | ||
| 17 | "The Hippos" | September 20th, 2017 |
| Returning home from an African river, the Octonauts greet a group of hippos. | ||
| 18 | "The Yellow Bellied Sea Snakes" | September 13th, 2017 |
| A mass of poisonous sea snakes are stranded on a beach and Peso helps get them back to the ocean. | ||
| 19 | "The Loneliest Whale" | October 1st, 2015 |
| A lonely whale sings a song for the Octonauts. | ||
| 20 | "The Spinner Dolphins" | October 27th, 2017 |
| The Octonauts struggle to save a pod of spinner dolphins. | ||
| 21 | "The Coelacanth" | May 29th, 2017 |
| While exploring a dark cave, the team discovers a prehistoric fish fossil that moves. | ||
| 22 | "Operation Deep Freeze" | December 15th, 2015 |
| Captain Barnacles runs into an old fox friend from the Arctic and they work together to prevent a group of penguins from falling into an ice chasm. | ||
| 23 | "The Emperor Penguins" | January 13, 2016 |
| It’s a dangerous trek over ice, but the Octonauts help a penguin mother find her family. | ||
| 24 | "The Tiger Shark" | May 27th, 2017 |
| Tweak helps a sea turtle escape a hungry tiger shark. | ||
| 25 | "The Coconut Crisis" | May 19, 2016 |
| Someone is stealing the coconuts from the coconut crabs, so Kwazii investigates. | ||
| 26 | "The Sunfish" | May 28th, 2017 |
| The Octonauts help a giant sunfish who can’t swim in a straight line. | ||