One of the sites listed is:
It's just off the coast of Fremantle, but going beyond the beach of Carnac Island requires special permission from the Department of Conservation and Land Management. Anyone arriving by boat and thinking of sneaking inland while no one's looking could be in for a very nasty surprise, however. The island is teeming with tiger snakes. For researchers in highly protective clothing, this is handy for collecting venom for medical research. For an errant daytripper sauntering along in thongs, well, er … good luck.
Having dived with the seals at Carnac, and walked around a bit of the island in my youth, this was a surprise. Yes, we all knew the island had more than its fair share of snakes, which is why we were careful to wear our safety thongs.
The seals were extremely friendly by the way - a delight to dive with. You just don't want to go near them on land.