Conjecture Club Penguin has not given the subject a name - as such, the name Three Little Islands is purely conjectural. However, it will be used until an official name is released.
The Three Little Islands.
The Three Little Islands are tiny islands located northwest of Club Penguin Island, near the shore next to the Mountain; according to maps located in the Spy Headquarters and the Ship Hold. No one has ever visited them or found out much about them. It is possible they may just be map decorations. If the names are revealed, they may become rooms. It is highly unlikely that one of the islands is Rockhopper Island, as Rockhopper Island is sandy, and the three little islands look snowy. Also, they are too close to Club Penguin Island for one of them to be Rockhopper Island.
Trivia
One of these islands could be where Herbert is hiding