Oral histories that are likely to be accurate indicate that Austronesian Maori mariners from New Zealand made regular trips to Antarctica starting ca. 600s CE.
The paper is:
Priscilla M. Wehi, et al., "A short scan of Māori journeys to Antarctica." Journal of the Royal Society of New Zealand 1 (2021) DOI: 10.1080/03036758.2021.1917633 (open access).
For what it is worth, the abstract is poorly written, but the body text has some decent nuggets of insight.