Diving with Grey Nurse Sharks is an awe-inspiring experience.
Also known as Sand Tigers or more formally as Carcharias taurus, these sharks look scary.
They're big, with huge, very visible, teeth and they swim menacingly slowly.
But in reality they're relatively docile and are more interested in minding their own business than eating scuba divers or fishermen.
Why dive with these sharks? Not only are they beautiful to look at but they've also developed some fascinating traits.
Grey nurse sharks can grow up to 4 metres in length and they're generally already a metre long when they're born.
They are usually a brown/grey colour on their backs with white underneath.
These sharks have incredibly oily livers as a way of maintaining their buoyancy and they will also gulp air from the surface to help them float virtually motionless above the sea floor around deep gutters and rocky caves.
They love to eat fish, rays, crabs and lobsters.
These sharks have a fascinating reproductive cycle.
Embryos are grown in two uteri and when they get big enough they eat their yolk sac and then they'll eat each other.
Only two baby sharks will survive, one in each uterus.
Two years later, the mother gives birth to two one metre long miniature versions of adults...
complete with fully formed teeth.
In Australia, there are two main and separate populations of the grey nurse shark.
One along the east coast and one living on the west.
Unfortunately, these sharks have been hunted almost to extinction.
Along the east coast it's estimated there are less than 1000 individual animals left.
The grey nurse has the distinction of being the first shark in the world to become a protected species - way back in 1984.
Unfortunately since then, the east coast shark population has been moved from 'protected species' classification to a 'critically endangered' one, while the population along the west coast of Australia has moved to a 'vulnerable to extinction' classification.
They are one of the most popular sharks kept in public aquariums around the world as they adapt relatively easily to their captive environment.
But if you're a scuba diver the place you want to see these animals is in the wild.
There are still a few places along the east coast of Australia where you can do just that.
Along the New South Wales coast there's known aggregation spots in Byron Bay, South West Rocks and Jervis Bay.
Diving at these sites is truly amazing.
At certain times of the year you can be diving with 20 or 30 sharks at once, cruising around.
When you're next to one you realise how big 3 metres actually is and many of the larger and older animals are quite battle-scarred.
It is also an unfortunate fact that many of these sharks can be seen with fishing hooks hanging from their mouths.
I have to admit it can take a minute to get used to the sight of a large shark with big teeth cruising slowly towards you but generally if you stay still or gently move aside, you will be rewarded with a close up view of the animal sliding past you.