Sharp teeth, fangs and a potential sting in the tail - researchers have found a collection terrifying species of fish lurking below the surface at our most popular beaches.

The photographs were taken by scientists with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) on a research voyage off the coast of Sydney in NSW.

Some of the species included in the grizzly snaps are the scaleless blackfish - a tiny fanged creature, the eel-like idiacanthidae and the nightmare-inducing chauliodontidae with its comparatively massive front teeth.

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The scaleless blackfish (pictured) was one of the fish photographed by CSIRO researchers off the coast of Sydney

Chief scientist for the voyage, UNSW marine biologist Professor Iain Suthers, said he was amazed they were able to find so many on the tiny critters and the discovery will now change how researchers study juvenile fish.

'We had thought fish only developed in coastal estuaries, and that once larvae were swept out to sea that was end of them,' Professor Suthers said.

'But in fact, these eddies are nursery grounds for commercial fisheries along the east coast of Australia.'

However, the fish weren't the only thing found on the voyage, with four extinct volcanoes on the ocean-floor also discovered.

The chauliodontidae, complete with its massive front teeth, was another of the species snapped

The idiacanthidae, which looks similar to an eel, was also found on the voyage off Australia's east coast

The critters were found in a hotspot for lobster larvae, which surprised scientists on board the research vessel

The quartet of 'hotheads' were located about 200 kilometres off the coast of Sydney, thanks to the new ocean explorer being used by the CSIRO.

The discovery of the 50-million-year-old volcanoes was made more amazing by the fact they weren't even being looked for.

'Our new ocean explorer, RV Investigator, has discovered four extinct volcanoes 200 kilometres off the coast of Sydney, hidden under almost five kilometres of ocean,' a CSIRO spokesman.

A collection of the critters found by researchers during the voyage

Four 'hothead' volcanoes have been discovered about 200 kilometres off the coast of Sydney

'Investigator was actually in the area on other business... the ship is constantly mapping the sea floor as it travels, opening up a previously undiscovered and unknown world.

'Our previous research vessel could only map to 3000 metres, missing important geological features like the calderas. Investigator can map the ocean to any depth (although it's yet to find James Cameron).'

The cluster is 20 kilometres long and about six kilometres wide, and rises 700 metres off the ocean floor at the highest point.

Researchers were able to create a '3D flyover' of the 'volcanic cluster' hidden deep below the surface, which shows the spread in elevation

The 50-million-year-old cluster was found by a CSIRO research crew that was looking for different species of larvae

Researchers were able to create a '3D flyover' of the 'volcanic cluster' hidden deep below the surface, which shows the spread in elevation.

ANU geologist Richard Arculus said it was an exciting find.

'This is the first time these volcanoes have been seen,' he told AAP.

'It proves yet again that we know more about the topography of Mars than we do the sea bed in our own backyard.'

Sonar images of the in-line volcanoes show large craters in the top of each, which Professor Arculus said proves they have all erupted, possibly in an explosive manner.

'But there's no real chance (they) are going to erupt again ... these guys have been dead for a long time.