The Box Jellyfish (also known as a Sea Wasp) is a very dangerous creature that inhabits Australian waters. The Jellyfish has extreme toxins present on its tentacles, which when in contact with a human, can stop cardio-respiratory functions in as little as three minutes. This jellyfish is responsible for more deaths in Australian than Snakes, Sharks and Salt Water Crocodiles.
The Irukandji Jellyfish inhabits Northen Australian waters. This is a deadly jellyfish, which is only 2.5 cenimetres in diameter, which makes it very hard to spot in the water.
The Saltwater Crocodile has been reported to grow to lengths of 7 metres!, but the average size of a Saltwater Crocodile is 4 metres long. They are the world's largest reptile and are found on the northern coast of Australia and inland for up to 100 kms or more. They can crush your skull without even trying.
The Taipan is a large, fast, and highly venomous snake often found throughout Australia. The Taipan has the most toxic venom out of all the species worldwide, has a dark brown color and is often found in sugar fields where it hunts for rats.
Another serious threat for those that wish to explore the waters of Australia is the blue-ringed octopus - one of the most toxic sea creatures in the world found off the coast of Australia, New Guinea, Indonesia, and the Philippines. Even though the octopus is only the size of a golf ball, there is no known antidote for its powerful venom. It causes motor paralysis, eventually leading to cardiac arrest.
Known as the most venomous fish in the world, the stone fish lives on the bottom of the reefs, camouflaged as a rock. It lives above the Tropic of Capricorn but can be found in the Queensland Great Barrier Reef as well. It's venom comes from the dorsal area, that is lined with 13 spines, causing shock, paralysis and tissue death depending on the severity of the sting. First aid consists of immobilizing the venom by bandaging the affected area then applying a hot compress. The pain is said to be so excruciating that it leads to amputating the affected limb.
Known as one of Australia's most deadly creatures, the Brown snake has a venom which quickly kills if it goes untreated. Even young snakes are capable of delivering a fatal bite to humans.
The Great White Shark can be found in great numbers on the southern coasts of Australia and, even though they have often been depicted as fatal to humans, they do not target them as a prey. Many of the attacks we're not fatal, the shark only performing test-biting, out of curiosity.
The darkly colored spiders resembling tarantulas have fangs and chelicerae with ample venom glands, that can even penetrate fingernails or shoes. They can be found in the eastern coast of Australia, New South Wales, Victoria or Queensland.