Cave Coins is a medium difficulty stamp in Club Penguin, only available to be obtained by members. To obtain it, you must find the hidden coins on the first level of the cave levels in Puffle Rescue.
How to Obtain
Right below the starting tile at the beginning of the level, there is a small arrow pointing downwards. While standing on the arrow, you must take two steps down, three left, two down, three right, and two down. You will then reach a platform with the coin bag, and a teleporter back to start.
This stamp was released on August 30th, 2010, along with the other Puffle Rescue stamps.