Heard from a mate once that I could find sea snakes in the Irwin River estuary, in Dongara WA. I highly, doubt that this is likely, can anyone confirm?
Not as a permanent thing, although there's no reason why they wouldn't occasionally be found there. I have seen sea snakes off Garden Island and once even in Fremantle Harbour, but the yellow-bellied sea snake has been collected as far south as Esperance and Tasmania, so Dongara is well within their range.
Can't imagine it would be that reliable. Better would be farther north like the Broome Jetty in the wet season but even then you're not guaranteed to see one. Heh, only certain place I have heard of is the Rowley Shoals but it's not cheap to get out there!! If you're really keen to spot one down here it might be worth calling a fishing operator who works out at the Abrolhos Islands and see how often they spot them. Can't suggest anything else. Good luck!
I've seen lots of big, fat sea snakes from the jetty where they (used to?) feed the dolphins at Shark Bay, so I'd say Carnarvon would be a good starting point for the southern latitudes.
I can't remember which sp they were but quite often when we used to fish on the Western side of Rottnest Island for Sampson Fish we used to encounter Sea Snakes!! I thought they were strands of Kelp at first till the guy I fished with lifted 1 out of the water with the gaff, they were a darkish green on top and faded to a milky yellow on the underside, they weren't at all skittish and when put back in the water they hung around for a while, some even took a small Herring when offered. ( ͡° ͜ʖ ͡°) -ronhalling