Mentawai Strait separates the island of Sumatra from the small archipelago of the Mentawai Islands, Indonesia. Its waters belong to the Indian Ocean and both banks are part of the province of West Sumatra.

Mentawai Strait
Selat Mentawai (Indonesian)
Mentawai Strait
Mentawai Strait
Coordinates	1°45′00″S 100°0′0″E / 1.75000°S 100.00000°E / -1.75000; 100.00000
Type	strait
Basin countries	Indonesia
Max. length	450 kilometres (280 mi)
Max. width	150 kilometres (93 mi)
Min. width	100 kilometres (62 mi)
Settlements	Padang
References	Selat Mentawai: Indonesia National Geospatial-Intelligence Agency, Bethesda, MD, USA

The strait is about 450 km long and its width varies between 100 and 150 km. The main city on the edge of the strait is the capital of West Sumatra, Padang.

The strait is in major fault zone and several earthquakes have been located in it, being the most known those of 1833 Sumatra earthquake and that of 2009 Sumatra earthquake.