The Mentawai Islands are a chain of about 70 islands and islets off the western coast of Sumatra in Indonesia. Siberut is the largest of the islands.
The other major islands include Sipura, North Pagai (Pagai Utara) and South Pagai (Pagai Selatan). They lie approximately 150 km off the Sumatran coast across the Mentawai Strait.
The indigenous inhabitants of the islands are known as the Mentawai people.
The Mentawai Islands have become a noted destination for surfing.