Male southern fur seals are 154 cm long, while the females are about 120 cm long. Although there is a 30 cm difference, it is the least sexually dimorphic of otariids in size and in color. Dorsal body surface is gray-brown, the venter is light tan. Arctocephalus galapagoensis is the smallest of the fur seals, possibly an adaptation to the warm ambient and aquatic temperatures of their tropical habitat (Wartzok, 1991).

Range mass: 27 to 64 kg.

Other Physical Features: endothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: male larger