Kwazii and Barnacles re-taking the Octopod in "The Great Algae Escape".
Professor Inkling using the Octopod itself to wrestle a Colossal Squid.
"Amazon Adventure" is one long CMOA, from Kwazii tangling with sharks to retrieve the map to the Octonauts Big Damn Heroes moment during the climax.
"A Very Vegimal Christmas" features the Vegimals taking about a thousand friggin' levels in badass! They build a new GUP and rescue the Octonauts when they are trapped in a blob of marine mucilage. The cherry on top? They still manage to cook the Christmas dinner.