Steinsundøyna is an island in the municipality of Solund in Vestland county, Norway.

The 18.7-square-kilometre (7.2 sq mi) sits on the north side of the Sognesjøen, at the mouth of the large Sognefjorden.

The rocky island is virtually treeless (except in small, sheltered areas).

[1] The strait between Steinsundøyna and the neighbouring island to the west, Rånøyna, is called Steinsund.

Despite being less than 60 metres (200 ft) wide at the narrowest passage, it is shippable.