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).
... (1863-1942), India and Tibet
Z
Zhang Qian[?] - spent 12 years starting in 138 BC exploring much of Central Asia for Emperor Han Wu Di[?]
Zheng He, (1371-1435), Chinese ...