he is on the ship and you have to be a secret agent to do this
the migrator
The key is hidden in the bookroom the book shelf. It is at the back of the book "Rokhopper and the stowaway". Use the key to get into rockhopper' ship.
Rokhopper comes every two months or so and you will know because it talks about it in the newspaper and wen he is there go to the beach an his ship will be there.
Rockhopper's ship will be found at The Beach on any server on Club Penguin. He only comes for a limited time and then sails away again.
The key is hidden in the bookroom the book shelf. It is at the back of the book "Rokhopper and the stowaway". Use the key to get into rockhopper' ship.