Secret island

Have you noticed a secret island, which can be seen only during the flash in Shipwreck island?

Is this Rockhopper island or Dinosaur island or some third island?

It can be Dinosaur island because Dinosaur island has a volcano and many trees.

And it is next to Shipwreck island.

Or it can be some third island what is not in the map. It can be on the missing part of the map.

You can see that island in Club Penguin log in backgrounds and banners.