Octo Canyon is the main area for the story mode campaign in Splatoon 2, which the Octarians use as their home and the base of their operations, the last zone is a sea of acid and some giant stone octopus tentacles.
The player spawns on a small island in the middle of a canyon (hence the name) and is greeted by Squid Sister Marie. She takes on Captain Cuttlefish's role (he is on a research trip with Agent 3) and recruits the player as Agent 4 of the New Squidbeak Splatoon.
Throughout Octo Canyon, the player will search for invisible kettles and shoot ink at them to go into level, rescuing a Mini Zapfish if the player beats the level. After completing a certain amount of levels in a area, the player will be presented with a boss kettle, where they will attempt to defeat a boss with three phases.