|Where||Underground, below the Forest, east of Gold Mine|
|Opened|| January 22, 2010 (temporary)|
March 15, 2010 (reopening)
|Closed||January 28, 2010 (temporary)|
The Hidden Lake was a subterranean lake in Club Penguin. It opened out to the sea, and a variety of sunken treasure drifted here from underwater. Waterfalls flowed here into the sea from underground reservoirs.
During the Cave Expedition, the Hidden Lake was uncovered, along with other caverns. After the expedition, due to cave-ins at the Mine, the Hidden Lake was blocked off along with the other newly explored caverns. A few months later however, the rocks blocking the entrances eroded away, and puffles found their way in. Rescue teams were formed to rescue the puffles, and ever since, the Hidden Lake has remained open.
At the start of the Island Adventure Party 2010, a ladder was added to the northwest wall that could be climbed to access the Forest. During some parties, the ladder was blocked off, due to decorations at the Forest.
|Candy Apple Pin|
|Red Puffle Pin|
|Red Electric Guitar Pin|
|Crystal Ball Pin|
|Dub-step Puffle Pin|
|Coconut Smoothie Pin|
|Pixel Puffle Pin|
|Orange Slice Pin|
|Fishing Rod Pin|
- During the Cave Expedition, members were able to buy a Deep Sea Diving Suit.
- During the Island Adventure Party 2010 and Island Adventure Party 2011, it turned into a mermaid's cove, filled with pink algae, rocks, and shells.
- During Sensei's Water Scavenger Hunt, it was filled up with water. Floating water pumps were placed above the water.
- Prior to Operation: Puffle, and after November 2013 Tremors, the path to Cave Mine was blocked by large boulders. The Cave Mine was deemed unsafe, and was shut down permanently as a result, and was replaced with the Gold Mine.
Names in other languages
| Gold Mine|
Cave Mine (formerly)