I wouldn’t dip a big toe into the ocean in Australia.
Saltie crocs... huge Great Whites on the Barrier Reef and beyond.. and a whole lot of other dangers in that wild country.
Have to agree there- and for that matter in the outback— as regards the deadliest viper of all snakes— the Australian Brown snake (deadliest venom per measure). Would rather, if a choice was given, be bitten by a cotton mouth moccasin in the Okefenokee swamp (well... not really, but it would have some chance of recovery given an antivenin in time).