[1] Fischer Nunatak was mapped by Norwegian cartographers from air photos taken by the Lars Christensen Expedition, 1936–37, and named "Sornuten" (the south peak).

It is about 750 metres (2,460 ft) high, with an area of exposed rock that covers about 1 square kilometre (0.39 sq mi).

The nunatak has a long, smooth slope that is ideal for downhill skiing during the rare periods when there is enough snow cover.

The west side has abundant Buellia lignoides and Rhizocarpon flavum, neither of which is found on Mount Henderson.

[3] A specimen of Umbilicaria decussata collected on the nunatak is preserved in the Royal Botanic Gardens Victoria.