The Gulf of Boni (also known as Bone Bay or the Bone Gulf) is a large inlet in the south of the island of Sulawesi, Indonesia. To the west lies Sulawesi's South Peninsula, and to the east is the island's South-east Peninsula. To the south, the gulf opens into the Banda Sea.
The International Hydrographic Organization (IHO) defines the Gulf of Boni as being one of the waters of the East Indian Archipelago. The IHO defines its southern limit as: "A line from, Tg. Lassa, Celebes [Sulawesi], to the North point of Kabaena (5°05′S 121°52′E / 5.083°S 121.867°E) and thence up this meridian to the coast of Celebes".