The Dugong (Dugong dugon) is the smallest member of the order Sirenia (which also includes the manatees and Steller's Sea Cow). Adults are generally less than 3 meters long. The name Dugong originated from the Malay language 'duyung' meaning lady of the sea or mermaid.

Although they once covered all of the tropical South Pacific and Indian Oceans, remaining populations are greatly reduced. Groups of 10,000 or more are present on the Great Barrier Reef of Australia, at Shark Bay, and in Torres Strait south of New Guinea. Before 1970, it is thought that large populations were also present in Mozambique and coastal Kenya, but these have dwindled. Palau also has a small population. On January 22, 2003, after 70 years, an individual was found (weight 300 kg, length 2 m) off the coast of Tanzania.