Sibhinis, Siobhanais or Shivinish. is one of the Monach Islands, lying between Ceann Iar and Ceann Ear. It is tidal, and connected at low tide to Ceann Iar by Fadhail Shibhinis, and to Ceann Ear by Faodhail Chinn Ear. It is 16m at its highest point. It is said that it was at one time possible to walk all the way to Baleshare, and on to North Uist, five miles away at low tide. In the 16th century, a large tidal wave was said to have washed this away.
The island is about 22 hectares (54 acres) acres in extent.