The term ‘sublime’, the Oxford English Dictionary (OED) tells us, means ‘lofty’, ‘high up’ or ‘elevated’. More specifically it applies to ‘that quality in nature or art’ ‘that fills the mind with an overwhelming sense of grandeur or irresistible power’ (OED). In travel texts the sublime is often associated with an encounter with a natural phenomenon that stretches the observer's powers of imaginative comprehension to their very limits. As Philip Shaw (2006, 2) puts it, ‘[W] henever experience slips out of conventional understanding, whenever the power of an object or event is such that words fail and points of comparison disappear, then we resort to the feeling of the sublime.’ Majestic mountain scenery, limitless oceans and vast, solitary deserts invoke the sublime, particularly in the Romantic period when the response of the individual traveller was often seen to be a marker of the authenticity of the journey. In the present day awe and wonder remain part of the traveller's currency, although they are often reformulated into a postmodern take on sublimity.

Although the term had been present since ancient times (see, e.g., Chard 1999, 111), it was in the eighteenth century that Edmund Burke (1958) gave it the aesthetic dimension with which we continue to associate it. He proposed that the aesthetic emotion engendered by an encounter with the sublime in nature is astonishment held in suspension by a degree of horror that precludes all other rational activity: ‘In this case the mind is so entirely filled with its object that it cannot entertain any other’ (57). This state of being, associated with silence, melancholy, power and strength, is to be distinguished from the languorous pleasantness of beauty in nature, and from the picturesque, which lacks the terror associated with the sublime. These terms were central to the perceptions of travellers in the eighteenth and early nineteenth centuries, and the implied gendering is not to be underestimated: the masculine connotations of the sublime were inextricable from the image of the indefatigable, questing male.

The Romantic travellers most associated with these qualities are Byron, Coleridge, Shelley and Wordsworth. To these we might add Captain Cook, Joseph Banks and the ‘visionary’ traveller and collector William Beckford. Wordsworth is perhaps the most determined to articulate the effect of the sublime, not just on the mind of the traveller but also on the consciousness of the poet.