The present watercolour was executed on Cotman's second and last trip to Wales, in the company of Paul Sandby Munn in 1802. On the 19 July, Cotman and Munn reached the area around Dolgelly where they remained until 23 July, they then revisited Harlech, which they had discovered during the first trip to Wales in 1800. They then spent a day sketching at Capel Curig, from which they walked onto Llyn Ogwen before arriving at the Lanberis Pass on 28 July. The majesty of this mountain lake made a deep impression on both artists. Munn worked up his sketches into a large watercolour which he exhibited at the Royal Academy in 1803.
In his early works, such as the present watercolour, we see Cotman's vision of the romantic picturesque beginning to develop, and we also see his sense of the abstract design that was to play such a focal part in his painting. S.D. Kitson in his monogram The Life of John Sell Cotman, London, 1937, p. 43, described the Welsh tour of 1802 as 'the turning point in Cotman's artistic development'. In the present watercolour Cotman has successfully conveyed the mood of sheer magnificence and grandeur of the scene in his use of a sombre palette. A diminuative figure is placed in the foreground, dwarfed by the mountains rising into the clouds, the mood is sombre and mysterious. The greyish-blue tones are typical of his work at this period and show the influence of Thomas Girtin (1776-1802), whom he had met up with on his first trip to Wales in 1800, whose ability was at its height at that time.
Cotman returned to this subject in 1823-4 painting two more versions, one of which is in the Walker Art Gallery, Liverpool, the other Leeds City Art Gallery. Another version of the subject, executed in the late 1830s when Cotman was using a mixture of watercolour and flour paste is in the collection of the Rhode Island School of Design.