The Seychelles are a group of islands in the Indian ocean.
That depends on the location of the island itself.
San Nicolas Island
The exact location is Ontario .
somewhere
Crete Island ..
The main reason is probably because it doesn't matter what the island was called. If you knew precisely which island it was you would also know its location and this would distract you from the essential story. The location and name of the island are irrelevant, what matters is what takes place on the island, and this could happen on any island or any other remote location.
Cape Hatteras Lighthouse Location: Hatteras Island -->credit: thank the azn.
There isn't a location called Mystery Island.
Vancouver's relative location
It is.
Peru
There is no island at that exact location. The closest island to it is Penrhyn.