Bandon Bay (Thai: อ่าวบ้านดอน, rtgs: Ao Ban Don, Thai pronunciation: [ʔàːw bâːn dɔːn]) is a bay in the Gulf of Thailand in the Surat Thani Province, extending from the Sui cape in Chaiya district in the northwest to the Kanchanadit district to the east. The total coastline is about 100 km. The bay is dominated by the estuary of the rivers Tapi and Phum Duang.