Ringvassøya

or is a large island in Troms county, Norway. It is divided between Tromsø Municipality and Karlsøy Municipality. Several islands surround Ringvassøya including Kvaløya to the south; Reinøya and Karlsøya to the east; Vannøya, Helgøya, and Nordkvaløya to the north; and Rebbenesøya to the north west. The island is connected to the neighboring island (and the rest of mainland Norway) by the Kvalsund Tunnel on the south shore of the island.

With an area of 663 km2, Ringvassøy is the sixth largest island in mainland Norway. The island's highest point, Soltindan, has a height of 1051 m above sea level. The 10 km long Skogsfjordvatnet is the largest lake on an island in Norway.

The villages of Hansnes (the administrative centre of Karlsøy Municipality), Hessfjord, Indre Kårvik, and Skarsfjord are all located on the island. In 2018, there were about 1,300 people living on the island.