Duelist Island is a remote island shown in "Bokka Panic!" & "Gotta Catch 'Ya Later!". The only known visitors to the island who are ATA members in the OG continuity are Rocko & Filburt, but it's been suggested that The Gromble sailed there to get himself immortalized as a rare card.
In the Advanced saga, our heroes embark on a journey to the island to find which duelist owns the three Chaos Cards. During this arc, the island is wiped out and destroyed when Yusaku pulls a Torgarok: God of Destruction card. However, the cards survive, and are currently in the possession of Simon.