Ducie is the easternmost island of the Pitcairn Group, being located 470 km north and east of Pitcairn Island. The island is a small atoll formation (with a land area of 0.7 km²) consisting of one large islet (Acadia) on the northern side and three smaller islets (Edwards, Pandora and Westward) on the southern side. They enclose a shallow and sandy lagoon of around 1.5 km across that contains numerous coral ridges and patch reefs. The entire atoll is surrounded by a fringing reef with broad reef flats on all sides except the north. The main island has an atoll forest dominated by Tournefortia argentea. Ducie is an important location for seabirds with around a dozen species breeding on the atoll, including what is thought to be the world's largest breeding colony of Murphy's Petrel (Pterodroma ultima) with around 250,000 pairs.