Central Station

Central Station, or Deep Sea Central Station as it is commonly referred to as, is the primary hub and starting point of the Octo Expansion.

Gameplay
After completing the tutorial station, Agent 8 and Cap'n Cuttlefish will find themselves at the Central Station. No weapons are allowed in the area. On an initial play through the only things of note in this station is the actual metro, which can be boarded in order to access the other station, and Telephone, who will act the primary catalyst of the Octo Expansion. After completing any of the Thang stages, Agent 8 will return to the Central Station with the Thang.

Postgame
After completing the Octo Expansion, Agent 8 can return to Central Station in order remember and replay the final act of Octo Expansion or watch the credits.

Additionally, after completing Octo Expansion, a vending machine will now be functioning, the vending machine will accept either exchanges of either 15000 CQP or Mem Medals. The vending machine will randomly give items, including Food and Drink tickets, Coins, and Ability Chunks in varying quantities.

Secret Boss
Upon completing all the Test Chambers and collection all the Mem cakes, Agent 8's final memory can be unlocked. An open locker will trigger a battle with their "Inner Agent 3". This acts as a Secret Super Boss in Octo Expansion. Beating this boss will reward players with the Golden Toothpick gear piece.

Compared with the Spinal Phase battle, Agent 3 still uses the Hero Shot, but is much more aggressive, has higher health, throws Autobombs instead of Splat Bombs, and uses a completely different set of special weapons. Additionally, the arena is much smaller and has no inkable walls. An aggressive approach is vital in maintaining turf control in the arena, and since Agent 3 dodges more often the player must make sure every shot counts. It is also a good idea to try and box in Agent 3 so they cannot evade attacks as easily.

Phase 1
Agent 3 will attack with the Inkjet in this phase to supplement the Hero Shot and Autobombs; while they are vulnerable during the special, it is equally important not to stay put long enough to take damage in the process. As before, Agent 3 will Super Jump to the UFO when enough damage is taken, Super Jumping back with a Splashdown to begin each subsequent phase.

Phase 2
Agent 3 will now use the Bubble Blower, which will both protect them and let them cover large amounts of turf at once. However, Agent 3 is exposed when using it and cannot react fast enough to avoid attacks at Short range.

Phase 3
Agent 3 will use an Autobomb Launcher, deploying up to 4 Autobombs at a time. As the player will likely be surrounded by Autobombs if Agent 3 is left alone, taking them down quickly is advised- with fast enough reactions, the player can progress to the next phase before Agent 3 has a chance to use the Autobomb Launcher.

Phase 4
Agent 3 launches Tenta Missiles from the UFO; while dangerous to attempt, two Splat Bombs thrown in quick succession will end this phase.

Phase 5
Agent 3 uses a similar sequence of three Splashdowns as they did in the earlier boss fight, but the Splashdowns are executed much faster and there is less time to react in between each one. The player will likely get only one chance to finish off Agent 3 before they use the Splashdowns again, as the reduced mobility from losing turf control will otherwise be fatal.

Trivia

 * In a screenshot released shortly after the announcement of the expansion, this station was shown on the Deepsea Metro map. At that time, the translation was not yet finalized, and the station's subtitle was "Promise land here we come!"