The Steller sea lion (Eumetopias jubatus, also known as Steller's sea lion or the northern sea lion) is a large, near-threatened species of sea lion, predominantly found in the coastal marine habitats of the northeast Pacific Ocean and the Pacific Northwest regions of North America, from north-central California to Oregon, Washington and British Columbia to Alaska. Their range continues across the Northern Pacific and the Aleutian Islands, all the way to Kamchatka, Magadan Oblast, and the Sea of Okhotsk, south to Honshu’s northern coastline. It is the sole member of the genus Eumetopias, and the largest of the so-called eared seals (Otariidae). Among pinnipeds, only the walrus and the two species of elephant seal are bigger. The species is named for the naturalist and explorer Georg Wilhelm Steller, who first described them in 1741. Steller’s sea lions have attracted considerable attention in recent decades, both from scientists and the general public, due to significant (and largely unexplained) declines in their numbers over an extensive portion of their northern range—notably in Alaska.
Adult animals are lighter in color than most sea lions, ranging from pale yellow to tawny and occasionally reddish. Steller sea lion pups are born almost black, weighing around , and remain dark in coloration for several months. Females and males both grow rapidly until the fifth year, after which female growth slows considerably. Adult females measure in length, on average being , and weigh , with an average of . Males continue to grow until their secondary sexual traits appear in their fifth to eighth year. Males are slightly longer than the females, growing to about long and averaging in length. Males have much wider chests, necks, and general forebody structure. Males can weigh between , weighing on average . Males are further distinguished from females by broader and higher foreheads, flatter snouts, and a thick mane of coarse hair around their large necks. It is fitting then that their Latin name translates roughly as "maned one with the broad forehead".