Wow! This place is the Hidden Lake...
Where did all this treasure come from, I wonder... And it looks like there's a door under the water.
Hidden Lake is a subterranean lake in . It opens out to the sea, and a variety of sunken treasure drifts here from underwater. Waterfalls flow here into the sea from underground reservoirs.
Club Penguin Rewritten
An underwater door here leads to the
Underwater, but the door can only be opened with the Moss Key Pin.
A broken Aqua Grabber sub is seen in the bottom left corner.
One instrument from the Instrument Hunt was also hidden here, in the broken Aqua Grabber sub.
The key to the Underwater area, mainly called the Moss Key Pin, can be obtained by following the silhouette of the giant squid in Puffle Rescue to a reef with a secret entrance to the area itself.