Some fans claim that Peso, Shellington and (sometimes) Barnacles doesn't need the oxygen system underwater, as oxygen tanks and helmet, but in Real Life those creatures really can't breathe underwater. They only can contain the respiration for a while.
In the Narwal episode, imagine if the titular narwal, Boris wasn't in the same place as the Octonauts when they were trapped in the ice...
The Giant Comb Jellyfish episode. Peso and the jellyfish were draged by a sea stream, far from the Octopod with Peso is trapped inside the giant jellyfish. But after being free (and the jelly apparently trapped accidentally) a hungry great white shark chased Peso, and he almost eat him, actually swimming faster than Peso. He was so lucky for reunites again with the giant jellyfish. But imagine if not. The Octonauts tracked him by an implant. So, imagine if the shark ate Peso, the Octonauts would found Peso... as shark poop. Obviously it can't happen due to being a children show, but would be incredibly disgusting and sad.
