Kotabaru Regency is one of the eleven regencies in the Indonesian province of South Kalimantan. It consists of two parts; the smaller but more populated insular part comprises Laut Island, the largest island off the coast of Kalimantan, together with the smaller Sebuku Island off Laut Island's east coast and other even smaller islands nearby; the larger but less populated part consists of the 12 districts on the mainland of Kalimantan. From Wikipedia
