Siutghiol (Romanian pronunciation: [ˈsjut.ɡjol]) is a lagoon on the shores of the Black Sea, in Constanța County, Northern Dobruja, Romania. It has a length of 7.5 km (4.7 mi) and a width of 2.5 km (1.6 mi); it extends over 20 km² (7.7 sq mi) and has a maximum depth of 18 m (59 ft).

Siutghiol
Lake Siutghiol
Siutghiol
Location	Dobruja
Coordinates	44°14′47″N 28°36′00″E / 44.24639°N 28.60000°E / 44.24639; 28.60000
Basin countries	Romania
Max. length	7.5 km (4.7 mi)
Max. width	2.5 km (1.6 mi)
Surface area	20 km2 (7.7 sq mi)
Max. depth	18 m (59 ft)
Islands	Ovidiu Island
Settlements	Ovidiu, Mamaia

Ovidiu Island is a small island on the west side of the lake, 500 m (550 yd) from the town of Ovidiu.^[1] On the east side of the lake is the resort town of Mamaia, which lies on a strip of land 8 km (5.0 mi) in length and only 300 m (330 yd) in width, between the Black Sea and Lake Siutghiol.