An Australian speleological pioneer (that's caving to the uninitiated), he has been appointed a member of the Order of Australia in the Australia Day honours list for ''significant service to the exploration, science and conservation of caves and karsts''.

Those few words mask a lifetime of effort that have, on occasion, taken him to places that would seem a more likely setting for Indiana Jones than an unassuming Canberra school teacher.

His published works include a comprehensive guide to our region's spectacular cave system, Wee Jasper Caves, a book entitled Jenolan Caves Guides, Guests and Grottoes, The Caves of Thailand - which is the result of many trips to that country, Jenolan Caves as they were in the 19th Century , Conserving Australia's Caves and The Exploration and Speleography of Mammoth Cave, Jenolan. The latter work, which was published in 1971, was the first book on the survey and study of a single Australian cave and a significant contribution to what was then the very sparse literature of caving.

Dunkley, who was born in Sydney in 1943 and went to the West Ryde and Eastwood primary schools before starting high school at what was then Fort Street High, recalls being fascinated by Jules Verne's Journey to the Centre of the Earth and a movie based on it when he was a boy. He was also mesmerised by the caving passages, based on a real cave system near Hannibal in the US, in Huckleberry Finn but realised that both were works of fiction.

The book that changed his life was Ten Years Under The Earth, a description of cave exploration in Europe including some of the systems famous for their galleries of prehistoric art, written by the French speleologist Norbert Casteret, one of caving's first gurus. The book was published in French in 1933. It was not translated into English until after the war and a copy fell into Dunkley's hands in the late 1950s.

Australian speleology was in its infancy, with the first association formed in Tasmania only in 1946. A Sydney club was formed in 1948. ''Australian caving is a postwar phenomenon,'' Dunkley said.

This is curious given that Wellington's cave system was already being explored in the first half of the 19th century and the work by, among others, Dunkley himself has shown that this continent has some of the most extensive cave systems on Earth.

Dunkley, who was president of the Australian Speleological Foundation from 1983 to 1986 and has been a life member since 2007, has surveyed more than 500 caves in Australia and Thailand in a remarkable career of exploration. He nominated his involvement in surveying the Bullita Cave System in the Northern Territory as one of the highlights.

''I worked on that from the 1990s until five years ago,'' he said. ''We were told of a cave that was reported to be six kilometres long and a group from Canberra started mapping it.''

A ''maze'' cave system, Bullita turned out to have multiple entrances and more than 122 kilometres of passages. ''It takes a long time to survey something this big,'' Dunkley told Fairfax Media.

While, like many cavers, Dunkley was first attracted by the obvious beauty of ''decorated'' caves such as Wee Jasper, Wellington and Jenolan with their delicate limestone formations and pastel colours that come to life under lights, his tastes quickly matured.

''My first real limestone cave was Junction Cave at Wombeyan,'' he said. ''It was a tourist cave, quite well lit, with some large chambers and well decorated - it was an attractive cave.

''I quickly became blasé´ about common decorations; there is an awful lot of it. I am most interested in large and impressive caves and the sheer spectacle of chambers such as at Abrakurrie on the Nullarbor. One [chamber] is as big as a sports field, it is 300 metres long, between 50 and 60 metres wide and 20 to 30 metres high.''

Dunkley said the sheer antiquity of most cave systems was almost impossible for people to comprehend. The limestone chambers at Jenolan, for example, existed before the Blue Mountains were first formed. ''The uplift that created the mountains bought the chambers close to the surface.''

One of the most remarkable things about the modest Canberran's contributions to caving, conservation and science is that they were achieved while he was living a busy life as husband, school teacher and mentor.

''My father was a fireman and mum was at home,'' he said. ''My younger sister and I had a conventional upbringing and I was able to go to Sydney University with the aid of a Commonwealth scholarship.''

He studied economics, which he concedes is rightly named ''the dismal science'' and taught it for the first 10 years of his career. ''I despaired of it [economics] then and I despair of it now,'' Dunkley said. ''It just doesn't deliver the answers it appears to promise to the problems facing people.''

Originally a member of the NSW teaching service, Dunkley switched to teaching geography and later in his career became interested in teaching legal studies. He married his wife, Jeanette, who he had met through caving, in 1970.

His experience with the ACT teaching service dates back to when it was first established in January 1974. ''We had been living in Sydney before that.'' Over the next 23 years until his retirement in 1997, Dunkley taught at almost every high school in the territory including Narrabundah, Weston Creek, Melrose High and Lake Ginnindera College.

''I enjoyed face-to-face teaching,'' he said. ''You could see the results of what you were doing, which is what it is all about. It is great to see kids make progress and then go on to other things beyond what you have taught them. Passion is important in just about any part of life, whether it is teaching young people or in caving.''

Dunkley said he'd had some good role models over the years including several prominent Australians whose ''underground'' activities were not widely publicised at the time. ''Justice Mary Gaudron was a member of our society until her work commitments intervened and Dick Smith was a passionate caver.''

They, like Dunkley and most Australian speleologists, were drawn to the activity by a high degree of curiosity and the realisation that contrary to popular belief, large parts of Australia remain uncharted and unexplored. ''But much of it is underground,'' he said. ''With a mountain you can see that it is there and you know where the top is. When you start exploring a cave you don't know how far the passages go or how deep it is. There is still so much to discover.''