An international group of scientists have used new technology to plumb the dark depths of Australia's eastern abyss for the first time, revealing an exciting array of rare sea life but also rubbish a kilometre under water.

A month after the CSIRO's research ship set off from Tasmania on a voyage into the unknown, the scientists have arrived in Queensland.

Forty scientists, representing 14 organisations and seven different countries, have come together on the RV Investigator to explore Australia's eastern waters.

Dr Tim O'Hara, from Museums Victoria, is the chief scientist of the project and he said it had been a fishing expedition like no other.

"It's really exciting — it's completely new and it's never been done before in Australian waters," he said.

Scientists caught a blobfish at a depth of 2.5 kilometres off the coast of New South Wales. ( Supplied: Robert Zelugaro )

The scientists have now completed their mission and along the way they have scooped up an exciting array of sea life and surveyed a world that had rarely been glimpsed.

New technology called 3D bathymetry data has revealed an extraordinary deep-sea landscape that plunges to depths of 4 kilometres.

"There's this whole world of mountains and plains and valleys and canyons," Dr O'Hara said.

The teeth of a cookie cutter shark, which feeds by gouging out cookie-sized chunks of flesh from prey. ( Supplied: Robert Zelugaro )

A specially designed camera dropped into the abyss and towed by the ship has given scientists a window into this hidden world.

As the camera lights sweep across the barren sea floor, occasionally a fish or jelly-like animal comes into focus and then disappears.

"We've never had the capability before," Dr O'Hara said.

"It's an amazing environment — there's no light down there, there's very little food, it's crushing pressure and it's a really hostile environment for life."

Human rubbish drops into abyss

The scientists also found a troubling amount of trash during the exploration.

The abyss drops to depths of 4 kilometres and so does the rubbish that people have been dropping into the sea for more than 200 years.

Scientists collect another net full of rubbish and mud from Australia's eastern abyss. ( Supplied: Robert Zelugaro )

"We've done about 50 different small net tows on the bottom and every one of them has brought up a piece of rubbish," Dr O'Hara said.

The array of litter includes old bottles, wire, ropes and plastic and burnt coal residue — known as clinker, dumped from old steam ships.

Researchers are also studying modern pollution, measuring micro-plastics in the oceans too.

"Everything we do on land affects things we do at sea and that filters down to the deep sea and into the abyss," Dr O'Hara said.

"We need to have that connection and know how we are affecting the animals down there, so I think it's been a really, really important trip for everyone."

Research assistant Phoebe Lewis with rubbish recovered from the depths. ( Supplied: Robert Zelugaro )

'Weird world of dead, rotting carcasses'

Throughout the journey, scientists have catalogued some of the extraordinary sea life that survives in that harsh world.

A friendly looking red coffin fish is the deepest one collected in Australia and may be a new species.

Dragonfish found in Australia's eastern abyss. ( Supplied: Robert Zelugaro )

Meanwhile, a bioluminescent cookie cutter shark that feeds on big fishes and an occasional unfortunate swimmer, gouges out cookie-sized chunks of flesh from its prey.

Scientists have also caught a comical-looking blobfish at a depth of 2.5 kilometres off the coast of New South Wales.

The first one collected in the Tasman Sea in 2013 became a social media sensation.

Deakin University researcher Jasmin Bursic with a whale skull. ( Supplied: Robert Zelugaro )

Researchers have found dead animals including a manta ray and a whale skull, which have also delivered an exciting range of sea life for the researchers.

"That was a kind of a weird world of dead, rotting carcasses," Dr O'Hara said.

"Ultimately there's no light down in the deep sea so there's no plants, so really the only source of food is dead things floating down from the surface."

Scientists found hundreds of samples of a very specialised group of animals that can digest bones, including giant sea fleas, pill bugs and 'zombie worms' that use bacteria to digest all the goodness out of the bones.

RV Investigator's deep sea exploration to continue

Melanie McKenzie, who heads the Invertebrate Collection at Museums Victoria, said the information gathered on the trip was critical.

"We need to protect our marine parks and we need to know what's there so we know how to protect them," she said.

"The only way we can do that is to find out what's there first, to get that baseline."

This expedition is over, but the research work has just begun and ultimately the collections will become publicly available through the CSIRO and state and national museums.

"We're going to have these animals and preserve these animals and footage and photos for so many years to come and it's just going to feed into so much different research," Ms McKenzie said.

The RV Investigator's deep sea exploration will continue over the next two years.

The ship is slated to survey the north-west shelf of Western Australia and the Tasmania Seamounts.