That is the area of the Great Barrier Reef and associated islands etc. Or are they talking about (on their map stamp) the area under the sea? Is it even a reference to the fabled lost land of Mu in the South Pacific? (reaching here, out on a limb)
I wish I could see all the words on the stamps, too small for me.
Fascinating that someone would go to all that trouble to do that. Is that a fantasy or science fiction type of book that is popular down there or something?