Well, to get to Rockhopper's quarters, you have to
1. Go to the bookroom
2. Look at the books, and choose rockhopper's journal
3. Flip to the back of the journal, and find rockhopper's key (Also a pin)
4. Go to rockhopper's ship, and go to his room
There is a treasure hunt game, where two people hunt for treasure
Hope you can get the chance to play it!!!