The oak of Vaišniūnai is an exclusive oak protected by the Ignalina District Municipality and a natural heritage site located in the Ignalina district, Vaišniūnai village. The oak's height is 18 m, volume - 3,18 m, it grows near the main road (road 1423 Aza-Vaišniūnai-Ginučiai-Kirdeikiai). During the interwar period the oak was used a Lithuanian - Polish demarcation line, and a border post was built.