Males of the species (Mirounga leonine) could theoretically mate with any female at all - such is their range.
SOUTHERN ELEPHANT SEALS
The revelation comes from a genetic analysis of the marine mammals published in the journal Science.
Researchers found one male, nicknamed Blob, which travelled 8,000 kilometres and fathered at least 19 pups.
Southern Elephant seal colonies ring the White Continent and the tip of South America.
Hunted animals
Anna Fabiani, from the University of Durham, UK, and colleagues studied animals on the Falklands Islands and nearby Elephant Island.
They took DNA samples from males and females to try to understand the breeding possibilities within these populations. The sequence data were compared with information on other seals around Antarctica that was already published.
Through the analysis, the researchers were able to confirm that females mature and breed close to their birthplaces while males travel and find multiple mates. The scientists say the males' search for mates is likely to make the gene pool in the species more uniform - although not necessarily less diverse.
Southern Elephant seals were hunted to the brink of extinction in the 19th Century for their oil.
The only other mammals thought to travel such great distances are whales.