|Where||Underground, below the Forest, east of Gold Mine|
|Opened||January 22, 2010|
|Closed||March 30, 2017|
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.
The Hidden Lake was first discovered during the Cave Expedition. An underwater door here led to the seafloor, but the door could only be opened with the key. After the Island Adventure Party 2010, a ladder could be climbed here in order to access the Forest.
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.
In November 2013, there were tremors in the underground, which caused the Cave Mine to collapse. After the rubble was cleared, the Hidden Lake led to the Gold Mine.
|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)