You will need a boat and favourable winds and tides to get to the island. Near to GZ you may be surprised to find signs of civilisation. After looking there you will need to look for a small black Sistema containing a log book and pencil.
There are ten islands of the Greater Palm group in the jurisdiction of the Palm Island Aboriginal Shire Council:
Curacoa (Noogoo or Inoogoo), Fantome (Eumilli), Great Palm or Palm Island (Bwgcolmen), Havannah, Brisk (Culgarool), Eclipse (Garoogubbee), Esk (Soopun), Barber (Boodthean), Falcon (Carbooroo) and Fly
Plus two islands in the Hinchinbrook jurisdiction, Orpheus (Goolboddi) and Pelorus (Yanooa) or North Palm Island.
All 12 islands now have a cache to find to encourage your visit.
Congratulations to Karicka for being the FTF.
