Almirantazgo Fjord, also known as Almirantazgo Sound (Seno Almirantazgo in Spanish), is a Chilean fjord cutting deeply into the Isla Grande de Tierra del Fuego. The fjord is a southeastern projection of Canal Whiteside, which separates the just mentioned island from Dawson Island. It is located at [1] and its south side branch out into several smaller fjords and bays, which significantly indent the north coastline of the Cordillera Darwin.[2] Ainsworth Bay, one of those, is home to a colony of elephant seals.[3] Azopardo River empties into the head of the fjord.
Ainsworth Bay, fed by the meltwater of Marinelli Glacier is a notable inlet along the Almirantazgo Fjord. The Marinelli Glacier has been in a state of retreat since at least 1960, and the retreat continues to the present time of 2008.[4]