Babeldaob (also Babelthuap) is the largest island in the island nation of Palau. Its area, 331 km² (128 mi²), makes up over 70% of the area of the entire country, and about 30% of the population, with about 6,000 people living there. Babeldoab is one of the most undeveloped populated islands in the Pacific.
Babeldaob is located northeast of Koror and contains the site of the new national capital, Ngerulmud. Unlike most of the islands of Palau, Babeldaob is mountainous. It contains Palau's highest point, the 242 meter tall Mount Ngerchelchuus. Babeldaob's eastern coast has many sandy beaches, in particular north from Ngiwal to Ngaraard, and the island's western coast has a shoreline with many mangrove shrubs and trees.
Palau's second-most populous state, Airai, makes up the southern end of the island. The Airai airport is the nation's principal airport. The Koror-Babeldaob Bridge links Airai to Koror.
Babeldaob encompasses 10 of the 16 states of Palau, which are:
Babeldaob was the location to which 426 members of the Sokehs tribe were banished by the German Empire following the Sokehs Rebellion on Sokehs Island and Pohnpei. Japan as mandatory power after World War I administered the return of the Sokehs in stages between 1917 and 1927.
During World War II the Japanese garrison was composed of 21,449 IJA men under the command of Lieutenant-General Sadae Inoue and 8,286 IJN men under the command of Vice-Admiral Kenmi Itoh. Babeldaob was bypassed by the allied forces during the war.