Phang Nga Bay (Thai: อ่าวพังงา, RTGS: ao phangnga [ʔàːw pʰāŋ.ŋāː]) is a 400 km2 (150 sq mi) bay in the Andaman Sea between the island of Phuket and the mainland of the Kra Isthmus of southern Thailand. Since 1981, an extensive section of the bay has been protected as the Ao Phang Nga National Park. The park is in Phang Nga Province, at 8°17′N 98°36′E / 8.283°N 98.600°E.
Limestone cliffs with caves, collapsed cave systems, and archaeological sites are found about Phang Nga Bay. Around 10,000 years ago, when sea levels were lower, it was possible to walk from Phuket and Krabi.