Even Ian McKinnon is surprised how swiftly the ocean takes over. Less than a month after the once-proud HMAS Brisbane was scuttled off Queensland's Sunshine Coast to serve as the nation's newest international-standard dive experience, Nemo and his mates had moved in.

"Already there are small fish gathering around the ship's smoke stacks," says McKinnon, of Scuba World in Mooloolaba. "There's a wobbegong shark that has settled in on the floor of the galley. There's a bull ray under the bow of the ship and a poisonous lion fish at the stern, under the propellers."

Soon coral will begin to colonise on the submerged warship. "The algae is forming on the ship now," McKinnon reports. "When the coral blooms after the full moon on the first weekend of November, we expect some of that migrating coral to settle on the wreck."

McKinnon has run his dive operation for 25 years and was a leading campaigner to secure the Brisbane as a wreck site once the Federal Government decided to decommission it. The project has cost almost $4 million: the $700,000 that the ship was worth in scrap metal, plus the $3 million that the Queensland Government spent cleaning it up.

"Over 400 tonnes of metal had to come off the ship," says McKinnon. "All the copper wiring. All the asbestos. All the lubricants, the oils and the grease. They had to cut holes along both sides so divers could get in and out of the ship easily. They welded up all the compartments where divers might have got trapped."

The scuttling, on July 31, attracted a huge amount of publicity. The Premier, Peter Beattie, described the new artificial reef as "a unique diving experience" that would complement the Great Barrier Reef and "allow us to enter the valuable international dive market". An estimated 10,000 divers a year are expected to explore the last of Australia's Adams Class destroyers, which now falls under the protection of Queensland's Parks and Wildlife Service.

To satisfy environmental concerns, the ship was sunk at least a kilometre from existing reefs. Its keel rests on sand 27 metres beneath the surface. But because the ship is eight storeys high, the smoke stacks are just three or four metres beneath the surface.

McKinnon took his first customers down just two weeks after the ship disappeared beneath the waves. The interest has been enormous, he says. "I've got charters lined up already from Sydney and inquiries from Victoria."

Australians love to go diving on wrecks, he says. "And this one is different, because most wrecks are unsafe for novice divers. They can be very hazardous places. But this one has been specially prepared. There's nowhere people can swim in without being able to swim out again."

McKinnon is one of four dive operators who hold concessions for the site (the others are Sunreef Diving Services, Noosa Blue Water and the Sydney-based Heli Dive). He believes the Brisbane will soon become the most popular wreck site in Australia, a title held by the Yongala, a historic wreck in the Great Barrier Reef Marine Park near Townsville. "But you are not allowed by law to penetrate the Yongala. With the Brisbane you can go into the captain's cabin, the engine room, the boiler room ... divers love to explore. That's the thrill of wreck diving."

The Brisbane is the fourth former warship to be scuttled as a dive site, following HMAS Swan and HMAS Perth in Western Australia and HMAS Hobart in South Australia.

But McKinnon believes two factors will ensure that the Brisbane will prove the most popular: Queensland's larger tourist population and the warmer water off the Sunshine Coast. A two-dive package, including equipment, costs $195 a person.

MORE INFORMATION

Sink the Brisbane, http://www.epa.qld.gov.au.

Scuba World, phone (07) 5444 8595 or http://www.scubaworld.com.au.

Heli Dive, (02) 9420 9635 or www.heli-diver.com.