Sulu Archipelago

The Sulu Archipelago is a chain of islands in the Pacific Ocean in the southwestern Philippines, forming the northern limit of the Celebes Sea and the southern limit of the Sulu Sea. Rather than being a remnant land bridge, it represents the exposed edge of small submarine ridges produced by tectonic tilting of the sea floor. Its major islands, including Basilan, Jolo and Tawi-Tawi, are extinct volcanic cones, with Tawi-Tawi carrying a serpentine basement core overlain by limestone. The archipelago covers about 4,068 square kilometers and is organized into the three provinces of Basilan, Sulu and Tawi-Tawi.