what is the largest landmass in oceania
Report Abuse. technically Australia is an island and a country and a continent. but if u don't consider Australia an island it would either be New Guinea or one of the New Zealand islands (north or south)...but no matter what Australia is the biggest land mass in the region of Oceania.jburford93 Â· 8 years ago.s New Zealand the biggest island in Oceania and Australia the biggest land mass in Oceania. Add your answer.