The history of the Dutch ship Duyfken which reached Australia in 1606, is known from written texts which are like an account recorded from Indonesia:
https://archive.org/details/travelsofludovic00vartrich/page/250/mode/2upp.249-251.
Indonesians in 1500 knew that the Southern Cross was used by Australian aboriginals to travel. It is visible in the tropics from April-June but continually visible south from 25 degrees ( as city of Brisbane, Queensland).
"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 Javanese jong ships already plied the seas between India and China as early as 1st century CE, carrying up to 1000 people alongside 250-1000 tons of cargo." _wiki.
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The midwinter day at West Antarctic peninsula is 4 hours but is longer in Southern islands, indicating an actual experience. East Antarctica on the Circle has 2 hours midwinter and up to 4 hour days for a couple of months. A ship-wreck "of ancient design" was found at Macquarie island when first visited by Australians.
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. p 249-251
Cartas de Afonso de Albuquerque, Volume 1, p. 64, April 1, 1512
Liebner, Horst H. (2002). Perahu-Perahu Tradisional Nusantara. Jakarta.
"Majapahit-era Technologies". Nusantara Review. 2 October 2018.
Macquarie Island: a brief history — Australian Antarctic Division Archived13 June 2012 at the Wayback Machine.
The record of other ships is like this :"In 1773 James Cook and his crew crossed the Antarctic Circle for the first time but although they discovered nearby islands, they did not catch sight of Antarctica itself. It is believed he was as close as 240 km (150 mi) from the mainland".
Is the Indonesian story believable and were they likely the first to explore there?