Sundini is the northern section of the sound separating the islands of Streymoy and Eysturoy in the Faroe Islands. The southern section of the strait is named Tangafjørður.

Streymoy is the largest and most populated island of the Faroe Islands. The capital, Tórshavn, is located on its southeast coast. The name means "island of currents". It also refers to the largest region of the country that also includes the islands of Hestur, Koltur and Nólsoy.