Oppheimsvatnet is a lake in Voss Municipality in Vestland county, Norway. The 3.55-square-kilometre (1.37 sq mi) lake lies in the northern part of the municipality, about 3 kilometres (1.9 mi) east of the village of Vinje. The European route E16 highway runs along the northern side of the lake, right past Oppheim Church which sits in the small village of Oppheim, after which the lake is named. The village of Vasstrondi lies on the southern shore.