Prachuap Bay

Prachuap Bay อ่าวประจวบ
View of Prachuap Bay from the town with Khao Lom Muak in the southern headland, as well as some of the bay's islands.
Prachuap Bay อ่าวประจวบ Location off the coast of Thailand
Coordinates	11°48′50″N 99°48′50″E / 11.81389°N 99.81389°E / 11.81389; 99.81389Coordinates: 11°48′50″N 99°48′50″E / 11.81389°N 99.81389°E / 11.81389; 99.81389
Type	Marine bay
Primary outflows	Gulf of Siam
Basin countries	Thailand

Prachuap Bay (Thai: อ่าวประจวบ) is a bay in the western side of the Gulf of Siam or Gulf of Thailand. It is located in Prachuap Khiri Khan town, Prachuap Khiri Khan Province.

Prachuap Bay lies north of Ao Manao. It is open towards the east and is bound by steep limestone outcrops forming peninsulas to the north, at Khao Ta Mong Lai and to the south at Khao Lom Muak. There are four islands in the bay area, Ko Lak, Ko La and Ko Rom located towards the southern end of the mouth of the bay, and larger Ko Raet further off the shore.

Ko Lak Island in Prachuap Bay was the historic center of administration of Prachuap Khiri Khan Province and its silhouette appears in the provincial seal.