The snailfish was found at the bottom of the Mariana Trench in the Pacific Ocean, and breaks the previous record by almost 1,640 feet (500 metres).
The finding was part of an international expedition that also found many other new species at the extreme depths.The bizarre creature found is thought to be a snailfish, a 'ghostly' looking creature that has a tad-pole like body
They have large heads, small eyes and no scales, and are normally slightly larger than a human hand in length.
Dr Alan Jamieson, from Aberdeen University said: 'This really deep fish did not look like anything we had seen before, nor does it look like anything we know of.
'It is unbelievably fragile, with large wing-like fins and a head resembling a cartoon dog'.Scientists from Aberdeen University and Hawaii University captured footage of fish in more than 105 hours of video taken at the Mariana Trench.
This was done with an Aberdeen-built machine used to venture into deep waters, known as the Hadal Lander.
It is the UK's deepest diving vehicle and is equipped with a high definition underwater camera.
The 30-day voyage was run by Schmidt Ocean Institute's research vessel, Falkor.
Scientists carried out 92 dives across the entire depth range of the trench, which lies in the Pacific Ocean east of the Philippines and south of Japan, from 16,400 to 34,600ft (5,000 to 10,545m).
They were also surprised to have discovered a rare 'supergiant' amphipod, a shrimp-like crustacean that can be up to 11 inches (28cm) long and was originally discovered in New Zealand in 2012.
This is seen swimming with the snailfish in some of the footage. Dr Jamieson added: 'Knowing these creatures exist is one thing, but to watch them alive in their natural habitat and interacting with other species is truly amazing, we have learnt a great deal.'
The Hadal Ecosystem Studies, published online, will give researchers new insights into the complicated ocean ecosystems by looking not only at the deepest point of the trench but also at different depths.
'Many studies have rushed to the bottom of the trench but from an ecological view that is very limiting,' said Dr Jeff Drazen, co-chief scientist from Hawaii University.
'It's like trying to understand a mountain ecosystem by only looking at its summit'. Aberdeen University researchers, who have carried out 13 previous trips to the trench, say they have also set records by filming three other types of fish at previously unrecorded depths.
They also successfully reached the bottom of the Sirena Deep, the trench's deepest point at 34,600ft (10,545 metres), solidifying their deep-sea lander as the UKs deepest diving vehicle.
Dr Jamieson added: 'We are particularly proud of this vehicle given it was designed and almost entirely built in villages in Aberdeenshire in the Northeast of Scotland.'
Wendy Schmidt, co-founder of the Schmidt Ocean Institute in California, also involved in the expedition added: 'Rarely, do we get a full perspective of the ocean's unique deep environments.
'The questions that the scientists will be able to answer following this cruise will pave the way for a better understanding of the deep sea, which is not exempt from human impact.'
