Underground Tunnels

The Underground Tunnels are under the school. They have been visited by Lee many times. They appear to have been there for a very long time with the exception of all the new labs that have been seen. All doors can be accessed by three ways. 1. A Key-Card system 2. A keypad with a code and 3. A key-hole for one of the ancient keys.

Entrances
The Underground Tunnels can be accessed by many entrance points. These are all the entrances that have been seen throughout the series:
 * 1) The Library entrance (accessed by one of the keys or a key-card)
 * 2) A closet in the principal's office (accessed by one of the keys or a code)
 * 3) An elevator to the Brainwashing Room from Room 113b (a normal door)
 * 4) An additional set of tunnels under McAdams Mansion (an elevator)
 * 5) A hatch in Shop Class
 * 6) A hatch under the Outcasts' table in the cafeteria (located on top of the Pyramid)
 * 7) An additional set of tunnels under the Green Apple Splat Factory
 * 8) Coral Grove
 * 9) Elevator in the Serpent's office at the Hydra Casino
 * 10) MWF Loading Station (Keypad or key)

Rooms

 * Brainwashing Room (Key or key-card)
 * Robot Chamber (Keypad or key)
 * Alfred Ping's Office (Key-card)
 * Unknown MWF Lab (Key-card)
 * Pyramid Room (Hazmat arm to shut down rays-shield)
 * Submarine Base (Hazmat arm to shut down ray shields)

Rooms in the McAdams Mansion Tunnels

 * Council Meeting Room (Keypad or Key)

Green Apple Splat Factory

 * ancient keys.