Hans Steffen Hoffman (20 July 1865, in Fürstenwerder, Prussia – 7 April 1937, in Davos, Switzerland) was a German geographer and explorer of Aysén Region in western Patagonia. Steffen did also work as teacher, encyclopedist and historian. Steffen Glacier on the Northern Patagonian Ice Field is named after him.
His work in Chile begun in 1889 when he was contracted by the government of Manuel Balmaceda in Chile to work in the Pedagogical Institute of the University of Chile as teacher of history and geography among other things. He was later contracted to join the Chilean boundary commission to explore areas disputed by Argentina in what is now Aysén Region of Chile.
The areas to be explored were those affected by article 1 of the Boundary treaty of 1881 between Chile and Argentina:
- "The boundary between Chile and the Argentine Republic is from north to south, as far as the 52nd parallel of latitude, the Cordillera de los Andes. The boundary-line shall run in that extent over the highest summits of the said Cordilleras which divide the waters, and shall pass between the sources (of streams) flowing down to either side. …"
This article led to dispute between weather the continental divide would serve as boundary favouring Chile or the highest peaks favouring Argentina. The two interpretations coincided for most of the boundary but in Aysén Region there were great differences. Before the explorations of Steffen Chile had made only limited hydrographic recognitions along the intricate Pacific coast of Aysén. The inland areas in dispute had been mainly explored by Argentines, notably Francisco Perito Moreno.
Between 1893 and 1894 he explored with the Chilean Navy the basins of Palena and Puelo River. He explored Manso, Aisén and Cisnes River from 1896 to 1898. He then moved on to explore the channels south of Taitao Peninsula (46°S) mapping and describing Gulf of Penas, and then exploring and naming Baker, Bravo and Pascua Rivers. He did also cross the Isthmus of Ofqui. Following Pascua River Steffen and his companions were the first to arrive to O'Higgins Lake from the Pacific as well the first to explore its western arms.