His treatise Draft of a Physical, Geographical, and Historical Description of Icelandic Ice Mountains on the Basis of a Journey to the Most Prominent of Them in 1792–1794 was submitted to the Naturhistorieselskabet in Denmark in 1795, where it languished for almost a century.
During his research, Sveinn observed that glaciers move by creeping in a way analogous to the flow of pitch.
In Eldrit, Sveinn was the first person to describe the volcanic belt, which lies across Iceland from southwest to northeast.
His district stretched from Árnessýsla to Skeiðarár Sandur, including the Westman Islands, and was difficult to cross owing to the many unbridged rivers.
Doctors were very poorly paid in those days so, to support his family, Sveinn also fished at sea from a row boat and farmed.