They mainly feed on fish and cephalopods and haul out on sand, gravel, rocky, or pebble beaches.

[3] The South American sea lion is among the largest of and most sexually dimorphic of the eared seals.

[3] Adult males have large heads with short, upturned snouts and long manes which reach the shoulders.

[10] South American sea lions breed on beaches made of sand, gravel, rocks, or pebbles.

[5] South American sea lions consume numerous species of fishes, including Argentine hake and anchovies.

[5] They have even been observed preying on penguins, pelicans, and young South American fur seals.

[5] South American sea lions have been recorded to take advantage of the hunting efforts of dusky dolphins.

Estrus in females usually begins 6 days after the birth of a pup and soon after the copulations start with a peak in January.

On rocky beaches, males establish territories where females go to cool off, keeping them until estrous.

On cobble or sandy beaches, males have territories near the surf and monopolize females trying to get access to the sea.

[13][5] During the breeding season, males that fail to secure territories and harems, most often subadults, will cause group raids in an attempt to change the status quo and gain access to the females.

Subadults herd their captured pups and prevent them from escaping, much like adult males do to females.

Pups gradually spend more time in the nearshore surf and develop swimming skills.

[5] South American sea lions are observed to make various vocalizations and calls which differ between sexes and ages.

[20] Indigenous peoples of South America exploited this species for millennia and by Europeans around the 16th century.

Numerous reserves and protected areas at rookeries and haul-out sites exist for the sea lions.