Underground (disambiguation)

The Underground was a somewhat secret area that was released at the Underground Opening Party in May 2006. Afterwards, it was open to all penguins. The rooms in the Underground were the:
*Boiler Room, a room where you could read older editions of the Club Penguin Times. This could be accessed easily from the speaker in the Dance Club.
*Underground Pool (formerly known as the Cave), a room where you could swim. This could be accessed easily from the manhole in front of the Pet Shop at the Plaza
*Mine, a room where you could play Cart Surfer or Puffle Rescue. It could be accessed easily from the Mine Shack
*Mine Tunnels, a series of caverns only seen in Club Penguin: Elite Penguin Force. Gary became lost here while searching for the runaway Test-Bots. Later in the game, the Protobot is built here. In Club Penguin: Elite Penguin Force: Herbert's Revenge, these caverns were turned into an EPF training area
*Underground (room), an additional room that was added during the Norman Swarm Has Been Transformed play at the Stage. It was located under the Stage
*Cave Mine, a dark and spacious cavern. It was a place to dig for treasure, first discovered during the Cave Expedition. However, in November 2013, it was closed off permanently due to tremors
*Hidden Lake, an underground lake connected to the sea. It opened during the Cave Expedition. It could be accessed from the Cave Mine or from a ladder hidden under a boulder at the Forest
*Underwater Room, a members only room, that opened at the Cave Expedition. It was accessible again by following the Giant Squid in the Puffle Rescue Black Puffle Level 1, and picking up the Moss Key in this room allowed permanent access, even if you were a non-member
*Gold Mine, a cavern filled with gold. You could dig for coins here using a Hard Hat or a Snow Shovel. It could be accessed from the Mine or Hidden Lake. This room was an adoption center for gold puffles