Vigdarvatnet is a lake in the municipality of Sveio in Vestland county, Norway. A small arm off the main lake juts to the south and runs along the municipal-county border between Sveio in Vestland county and the town of Haugesund in Rogaland county. The 10 km long lake forms a U-shape. It is fed by the nearby lake Stakkastadvatnet to the south, and it empties into the Ålfjorden, a small fjord arm off the main Hardangerfjorden. The village of Sveio lies on the northwestern shore of the lake.