Do they know how old these are? Maybe some family went down there while on a tour or something like that and carved there names and other glyphs they knew as a joke or something?
Hi Pharaoh Kel, according to Paul White's 1996 article the hieroglyphs are in some places very eroded suggesting a very old age from hundreds to thousands of years.
The hieroglyphs located in New South Wales, Biscayne Park do tell a story. Using archaic hieroglyphs that predate the Middle Kingdom. They tell the story of Egyptian sailors shipwrecked in Australia. Their leader Lord Djes-ed, a royal leader, after two years of working his way westward. Is felled by a snake bite and dies in "this wretched land" and recieves burial there. ( i like the wording 'wretched land' because that is how, especially later period, Egyptians felt about any land other than Egypt.) Three kings are mentioned in the glyphs, Ra-jedef, King of Upper and Lower Nile, the son of Khufu, the son of Sneferue. Placing the tale, and glyphs into the 4th Dynasty.
There is of course much controversy over the glyphs. Are they real or a fraud? There has been no artifacts recovered to support the tale of the glyphs. While some hieroglyphic experts point out that some of the glyphs are written backwards (misspelled so to speak). However this isn't such a problem because as one pointed out if the leader Lord Djes-eb was dead it is possible that their best speller and writer was dead as well. Another aspect is that if the glyphwriter was left handed and not an real expert he might have made some glyphs "backwards".
The Egyptians espeically in the Earlier Periods were well known traders. Khasekhmewy, 2nd Dynastic Pharaoh is the first known Pharaoh to trade by sea with Byblos. The huge ships such that Hatshepsut sent to Punt were known as Byblos ships. These ships date back to Egypt's earlist dynastic period as well.
Dr. Steve Young a speicalist in Ancient Ships even suggests that the Egyptians might have gone to Ur and other Mesopotamian cities by sail during the Predynastic period. Sailing from Red Sea ports of which a few certainly do date back as far as the Predynastic period, he suggests the Egyptians might have made it into the Persian Gulf to trade.
It is known that during the time of Cleopatra IV, one could sail to India from Egyptian ports.
One of Egypt's surviving stories is one about the Shipwrecked Sailor. If Lord Djes-eb, party had been shipwrecked on a trading venture to Punt, the Persian Gulf states, or even to India. There would have been no record of his voyage because he didn't return.
From the Red Sea, his most likely place of departure from Egypt it isn't hard to enter the Indian Ocean. A freak storm, a bad storm could have sent his ship, ships thousands of leagues off course. As there is very little big islands between the Horn of Africa and Australia it is reasonable to believe that Australia was the best land fall he made before meeting his death in a 'wretched land' far from the Nile.
Thor Heyerdalh did prove that ancient seamen had better boats then originally thought, and being seamen they were able to live at sea for periods longer than planned if need be.