The Octonauts embark on an underwater adventure, navigating a set of challenging caves to help a small octopus friend return to the Caribbean Sea.
| Actor | Role |
|---|---|
 Simon GreenallCaptain Barnacles (Voice) | Captain Barnacles (Voice) |
 Paul PantingPeso (Voice) | Peso (Voice) |
 Jo WyattTweak (Voice) | Tweak (Voice) |
 Keith WickhamShellington/Inkling (Voice) | Shellington/Inkling (Voice) |
| MMichael C. MurphyTurnip (Voice) | Turnip (Voice) |
 Teresa GallagherDashi/Ryla (Voice) | Dashi/Ryla (Voice) |
 Rob RackstrawKwazii (Voice) | Kwazii (Voice) |