Cumberland Islands, archipelago in the Great Barrier Reef, off the eastern coast of Queensland, Australia. The group comprises more than 70 inner continental islands (land, not coral), including Whitsunday, Lindeman, Brampton, Molle, Long, Hook, Dent, and Hayman. The high-cliffed wooded chain, once inhabited by squatters and timber cutters, is now a reserve area. Discovered in 1770 by Captain James Cook, they were surveyed by Captain Phillip King in 1820 and were named for the duke of Cumberland (Henry Frederick), a brother of George III.