Some islands are perfect for basking on the beach in the sun. But others are a little less relaxing - and Australia has some that are, in one way or another, a little bit scary???
  Quail Island, Northern Territory  
On the other side of the Cox Peninsula from Darwin, Quail Island is one you're frankly not going to get to at the moment. But this isn't necessarily a bad thing, as the exclusion zone around it is stopping you from getting a limb or two blown off. For decades since 1910, the military has used Quail and the nearby islands as something to fling rockets and bombs at. And, as such, it is covered in unexploded ordnance.
A clean-up operation began in 2011, in an attempt to make Quail Island habitable again, and is still on-going. 
  Wardang Island, South Australia  
Wardang Island might not be scary to most of us, but it should send chills down the spine of anyone in charge of a ship. A low-lying island on the western side of the Spencer Gulf, it has managed to amass nine shipwrecks - a pretty impressive achievement given that it only weighs in at around 20 square kilometres. Of course, this makes it a tremendous hang-out for wreck divers - especially ones that like being surrounded by little penguins. But a few nerves on the boat out there are entirely forgiveable.
  The Neptune Islands, South Australia  
Continue down to the end of the Spencer Gulf, and you'll come to the Neptune Islands. Which are delightful if you want to look at seals on rocks, but absolutely terrible if you fancy a swim. This is where Australia's only shark cage diving takes place - the great whites are eyeing up those seals too.
Calypso Star Charters (sharkcagediving.com.au) offers trips out from Port Lincoln - it's three hours in a boat each way, then passengers take it in turns to enter the cage, breathing through regulators and watching the apex predators of the sea flit past unnervingly close.
  Carnac Island, Western Australia  
There are several islands just south-west of Perth that are delights for wildlife lovers. Penguin Island and Seal Island give big clues in their names. But a bit further north, Carnac Island is not a place for casual frolics. Some rather brave boat tours head as far as the beach, but going inland is fraught with danger as Carnac is absolutely teeming with tiger snakes. No-one quite knows how they got there, although local legend has it that a showman released his collection after they killed both his wife and his partner.
  Fraser Island, Queensland  
Fraser is famed for its wild dingoes, which aren't all that scary as long as you're prepared to keep a respectful distance and not feed or antagonise them. The sea off the eastern coast is best avoided too - it gets somewhat sharky out there.
The real fear factor, however, comes in driving round it - especially for people who have perhaps conned themselves into thinking they have more 4WD experience than they actually have. Plenty of rented 4WDs have got bogged down, rolled over and caught out by the tides in the past. That said, the risk factor is part of the adventure - and anyone driving sensibly while taking adequate precautions shouldn't encounter many great difficulties.
See also: Dirty weekend - a girls' only weekend island trip with a difference
  The Governor Islands, Western Australia  
There are plenty of islands in northern Australia where the salties are basically in charge, but for croc-related terror it's hard to beat the experience of Kiwi kayaker Ryan Blair. In 2013, the New Zealander found himself held hostage by a six metre croc on the twin Governor Islands at the far north of the Kimberley. Every time he tried to get away, the menacing croc let him know in no uncertain terms that it was prepared to pounce on him.
Blair was eventually rescued by a local with a boat, and left all of his possessions on the island in his desperation to scape his crocodilian captor.
  Beacon Island, Western Australia  
Part of the Houtman-Abrolhos archipelago off the coast of Geraldton, Beacon Island was a grim place to be back in 1629. Dutch ship Batavia got shipwrecked there, and the would-be mutineers who were planning to take it over embarked on a mass slaughter of the other stranded souls. The story is absolutely remarkable, and human remains have been continually found there over time - the latest skeleton being dug up last year. Geraldton Air Charter (geraldtonaircharter.com.au) flies overhead and lands on nearby East Wallabi Island.
See also: The untouched Aussie island that played host to one of our darkest events
  Cockatoo Island, Sydney  
In the middle of Sydney Harbour, Cockatoo Island is now a bit of a fun in the sun spot, with a waterside caf&eacute;, giant chess set and rather scenic tennis court. But the island's history as a prison, school and dockyard gives it plenty of supposed ghosts. The stark former cells in the hulking sandstone buildings, plus the combo of quietness and relative isolation at night make camping out there an ideal opportunity to scare friends witless with spooky stories.
Biloela House, the former girls' reformatory, is reputedly the most haunted spot - look out for the ghost of an angry, red lady.
Disclosure: David Whitley was a guest of the South Australia Tourism Commission.
See also: Glamping at Australia's Alcatraz
See also: Australia's 20 best islands