Scientists aboard the CSIRO research ship RV Investigator have discovered new unnamed underwater volcanoes, a new species of deepwater coral and deep sea floor canyons during a 28-day voyage around the Coral Sea.

Key points: Research ship RV Investigator mapped the Coral Sea floor to better understand how it formed

Research ship RV Investigator mapped the Coral Sea floor to better understand how it formed Rock samples and possibly a new coral species are among a trove of discoveries

Rock samples and possibly a new coral species are among a trove of discoveries Chief scientist Jo Whittaker says many places they surveyed have never been sampled before

The voyage set out to gather rock samples from underwater volcanoes — called seamounts — to get a better understanding of how the region formed, and to map the seabed.

But scientists also discovered sea floor canyons 5 kilometres deep, new unnamed underwater volcanoes and what they believe to be a new species of deepwater coral.

They collected 650 rock samples, some from as deep as 4.5km and from areas never before surveyed.

The voyage's chief scientist, Associate Professor Jo Whittaker from the University of Tasmania, said the rocks would help answer important questions about the history of the Coral Sea and its formation millions of years ago.

Investigator made a string of new discoveries while surveying the deep sea floor in the Coral Sea. ( Supplied: CSIRO, Matthew Marrison )

"This is really a voyage of discovery in a lot of places," she said.

"A lot of these places haven't been sampled at all and so anything that we find is really is new and exciting — particularly in the far northern region of our voyage track, particularly in PNG waters — no-one's been there at all and there's just really been no samples collected.

"We turn out these beautiful mountain ranges and these beautiful extinct volcanoes and canyons, and just amazing features on the sea floor.

"It's just fantastic as you're just cruising along and you see this landscape appear in front of you."

While on board Investigator, scientists dredged bucketloads from the sea floor and gathered rocks from the Earth's mantle, below the crust, upon which tectonic plates move around.

This is believed to be a new species of deep sea coral. ( Supplied: Matthew Marrison, CSIRO )

Some of the underwater seamounts were up to 60 million years old.

With Australia moving north about 7 centimetres a year, investigators were keen to examine how the Australian plates moved through time.

"It explained there has been a lot of geological processes going on," Professor Whittaker said.

"We'll be able to take those rocks back to the lab and really understand what those processes are — the interaction between the movement of the tectonic plates and the circulation of the deep Earth."

She said another surprise they discovered was a coconut dredged from the sea floor nearly 4km down.

Voyage chief scientist Jo Whittaker said they had discovered some amazing features on the sea floor. ( Supplied: Matthew Marrison, CSIRO )

'Every day we made discoveries'

Teachers were also aboard Investigator participating in a CSIRO education program.

Olivia Belshaw from Jindabyne Central School in southern New South Wales said while on board she spoke live to classrooms across the country to share their discoveries.

"A lot of people, and a lot of students in particular, get it into their heads that science is old, it doesn't make any new discoveries, or if it does it's really rare," she said.

"We were able to talk to the kids about the fact that every day on that ship we made new discoveries.

"Kids actually got to understand that science is still all about discovery.

"There's that real sense of amazement and awe that they develop when they can see that people are still discovering things."

RV Investigator heads out again next week to study the East Australian Current, ahead of a longer voyage next month through the Great Barrier Reef to Darwin.