The first known European to reach Indonesia arrived in 1505.It seems Indonesians discovered the west Antarctic peninsula with a 4hr day in June but longer than 4 hr further north. It was not possible to travel further south in June.
"Ludovico di Varthema (1470-1517), in The travels of Ludovico di Varthema, stated that the Southern Javanese people sailed to "far Southern lands" up to the point they arrived at an island where a day only lasted four hours long and was "colder than in any part of the world"."
."mapping science was developed to the point that the Portuguese considered the Javanese maps were the best in the early 1500s."
The 4 hour day and Southern Cross are described here , click on pages 249-251:
https://archive.org/details/travelso...e/249/mode/2up
Jones, John Winter (1863).. The travels of Ludovico di Varthema in Egypt, Syria, Arabia Deserta and Arabia Felix, in Persia, India, and Ethiopia, A.D. 1503 to 1508. Hakluyt Society.