Bandon Bay 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 Tapi and Phum Duang rivers. The islands of Ko Samui, Ko Pha Ngan and Ko Tao enclose the bay from its eastern side. The bay is relatively shallow, with water depths ranging from 1 to 5 meters. Along the coast are mudflats owing to the high rate of sedimentation, which were naturally overgrown with mangroves (Sonneratia spp., Rhizophora spp.), but now mostly replaced by shrimp farms.