Probably executed on Richards's second trip to Europe in 1866–67, Lago Avernus is one of a handful of his early landscapes in watercolor. His interest in this medium was undoubtedly stimulated by the founding, at the time of his departure, of the American Society of Painters in Water Color, which would provide a forum for him and for many other American artists. In England Richards saw the watercolors of J. M. W. Turner, whose influence is conspicuous here in the subject (the volcanic lake near Naples that Turner had painted several times), the composition, and the mixture of transparent and opaque pigments, as well as in a textured blue paper very similar to that often used by Turner.

Lago Avernus may be the model for Richards's unlocated watercolor Lake Avernus, his first submission to the society, in 1870. In the same year he met Reverend Elias Lyman Magoon, who purchased many of the artist's watercolors of American scenery and gave them to the Metropolitan in 1880. The acquisition of Lago Avernus adds to our rich collection of the artist's work in various media, begun more than a century ago and enhanced particularly during the last decade.