‘Extreme’ in its most basic definition has a functional, navigational purpose designating the farthest distance from a centre. In this sense it may refer to geographical coordinates or to bodily ‘extremities’ – fingers, toes and so on, those parts of the human form which are most endangered should we venture to climactic limits at which frostbite becomes a possibility. ‘Extreme travel’ is not in the Oxford English Dictionary (OED) though by borrowing from the recently added entry for a similar concept, ‘extreme sport’, it could be defined as travel ‘performed in a hazardous environment or involving a great physical risk’ (OED). The wording is apt as it maintains the two types of ‘extremes’, environmental and bodily ones, though in extreme travel (as in extreme sport) the two often blur. Such a combination is what makes extreme travel perilous, and yet also, as Graham Huggan (2009) has noted, quite ubiquitous.

Why do individuals venture to far-flung places to put their bodies in danger? Answers may lie in the historical meanings of the word ‘extreme’. In early uses, ‘extremes’ is a synonym for ‘straits’, indicating travellers’ hardships and peril. Thomas Herbert (1634, 25) employs the term in this sense in writing of ‘Sea-men’ who ‘fell into great extreames’ in his Relation of Some Yeares Travaile. Given the semantic outgrowth of ‘travel’ from ‘travail’ (see travel), extreme travel is extreme suffering. However, such endeavours may be extremely rewarding. In late Latin, ‘extreme’ was used adjectively ‘as a positive, with comparative and superlative extrēmior, and extrēmissimus’ (OED). This sense blurs into another, fuzzier definition of the word ‘extreme’ as ‘a quality of condition, or feeling’ (OED), which further helps to explain the appeal of extreme travel. Romantic sensibilities desire extreme travel as a means of acquiring intense or profound mental experience in response to the perceived limitations of rigid and stifling norms. What Edmund Burke defined in 1757 as the ‘sublime’, the sensation of awe rooted in the possibility of pain, is in many instances located at the geographical extremes. Besides comprising physical space and the body, then, extreme travel should also take in the mind, especially sensory and/or emotional intensity. Commercial discourses on extreme travel continue to celebrate humans testing their physical and mental boundaries, often free of Burke's uneasiness.