A nunatak is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They often form natural pyramidal peaks. Isolated nunataks are also called glacial islands, and smaller nunataks rounded by glacial action may be referred to as rognons.

The Hudson Mountains are a mountain range in western Ellsworth Land just east of Pine Island Bay at the Walgreen Coast of the Amundsen Sea. They are of volcanic origin, consisting of low scattered mountains and nunataks that protrude through the West Antarctic Ice Sheet. The Hudson Mountains are bounded on the north by Cosgrove Ice Shelf and on the south by Pine Island Glacier. The mountains were volcanically active during the Miocene and Pliocene, but there is evidence for an eruption about two millennia ago and uncertain indications of activity in the 20th century.