I'll tell you this one. In the Hidden Lake (Under the rock in the forest), there is a door that has a big lock on it. Walk to the door and go inside. You've now gone into the Underwater Room. Put a comment below to say if this helped!!
noting
Not really, there's only a moss key pin and an underwater room (only for members).
you find it at the dance club
key
The Hidden Lake
You can buy a club penguin guide book. Then, look in the content for key merchandise and go to the page.
nothing
under the lounge
in the hidden lake
with a key!
in the library
it is in the mansion