Ilomantsi (Ilomants in Swedish) is a municipality of Finland.
It is located in the province of Eastern Finland and is part of the North Karelia region. The municipality has a population of 6,690 (2003) and covers an area of 3,172.86 km² of which 401.96 km² is water. The population density is 2.1 inhabitants per km². The most eastern point of the European Union is located in Ilomantsi.
The municipality is unilingually Finnish.
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