Note: Australia is generally considered to be a continental landmass, rather than an island. If however one does count Australia among the islands it, not Greenland, would be the largest in the world (unless one also considered Antarctica an island).
... 2000 to 5000 ft. The Western-Sakhalin Mountains peak in Mt. Ichara, 4860 ft., while the Eastern-Sakhalin Mountains's highest peak is Mt. Lopatin (1609 m, 5279 ft.) is also ...