Some penguins say it could be Rockhopper Island, but I think it could just be another part of the Club Penguin ocean because if you look on the EPF screen it shows you that the island is over to the left, but Rockhopper travels South when he leaves and the islands are closer to the West. But I'm just making that up, look at those three small islands to the left of Club Penguin. Where could that be?
This is just my predictions, I'm not really sure where it could be but maybe it could be an island that Herbert will wash up on shore and then start plotting, or if it is a tropical island he will stay there for all his life and never bother us again. But thats what I think, tell me in the comments if you have a suggestion and I'll post one or two to get your brains working! :D