Venomous, Poisonous, Dangerous, and other Wonders. Australia's most venomous snakes. Australia has over 140 species of land snake - and 32 species of sea snakes have been recorded in its waters-. Of these 100 species are venomous, although only a dozen are considered venomous enough to be fatal to humans. However, though Australian snakes are currently viewed as the most venomous in the world, they are, by no means, the most dangerous.