By Phil Mercer
BBC News, Sydney
Conservationists are urging the Australian government to protect the Coral Sea, one of its last tropical marine wildernesses.
The Coral Sea is one of few places home to hammerhead sharks
The sea was recently declared a "predator diversity hotspot" because of its abundant shark populations.
Campaigners fear the region could be targeted by illegal shark fishermen as well as oil and gas prospectors.
The Coral Sea comprises 780,000sq km, and borders the Great Barrier Reef off of Australia's east coast.
Environmental groups have described the Coral Sea as a stunning blue water highway full of oceanic predators.
The area is a haven for hammerhead and white-tipped sharks, as well as manta rays.
Wildlife groups want the government in Canberra to give it full environmental protection and create what would be the world's largest marine park.
Gilly Llewellyn, from the conservation charity WWF, says the region is likely to face serious threats in the future.
"It could potentially be targeted by illegal fishermen," she says.
"Sharks are increasingly rare in our oceans today. These are the sort of lions and tigers of the sea and unfortunately they are prized for their shark fin, which commands a high price in the Asian marketplace.
"So illegal fishers looking for sharks for their fin are becoming increasingly bold. Without formal protection for the Coral Sea we are afraid it might be vulnerable to that in the future."
An Australian government spokesman said that calls for the Coral Sea to be protected were being investigated by a specialist panel.
The area is considered to be one of the most spectacular diving destinations anywhere, largely because there are so many sharks in the water.
Campaigners, though, are asking just how long will it be before this pristine eco system faces potentially destructive challenges from the outside world.